The April Outlook

As the month progresses, normal average temperatures rise at the rate of one degree every three days. Beginning near 45 in central Ohio on the 1st of April, they reach to the middle 50s four weeks later.
Typical highs move from the upper 50s to the upper 60s. Lows advance from 35 to 45. A normal April in Yellow Springs has two days in the 80s, six days in the 70s, eight days in the 60s, eight days in the 50s, four days in the 40s, and two days in the 30s.
    According to my weather history, the warmest days in April those with better than a 40 percent chance for highs above 70 egrees) are the 21st, 23rd, and the 25th through the 30th. The 6th is the hottest day of all, with a 70 percent chance for 70s r 80s.
    The coldest April days, those with a 30 percent chance for highs only in the 30s and 40s: the 1st, 3rd, 4th, 5th, 6th (the 6th is the coldest of all, and the only April day with a 15 percent chance
for 20s), and the 9th. After April 22nd, chilly afternoons below
40 degrees occur less than once in a decade.
    Nightly chances for frost are 40 percent for the first half
of the month, but drop to only 20 percent by the 25th. The 26th and the 30th almost never have frost.
    An average April brings five completely sunny days, eight
partly cloudy days, and 17 totally cloudy days. The brightest
days in April (with better than a 70 percent chance for sun) are the 7th, 11th (the sunniest of all with a 90 percent chance), 16th, 18th, 19th, 20th, 24th, 25th, 26th, 27th, and 30th.
    Most precipitation usually occurs during the first two weeks
of the month. The wettest days (with better than a 60 percent
chance of rain) are April 3rd, 5th, 14th (both the 5th and 14th bring rain or snow seven years in ten), 29th and 30th. The days most likely to be dry (less than a 30 percent chance for precipitation) are the 11th,  12th, 24th, 26th, and 27th. 

Springcount
Twenty-three major spring cold fronts cross the nation between the middle of February and the last week of May. Three passed through in February, and seven in March – the ten fronts of the subseason, early spring. The first six April weather systems belong to the subseason of middle spring. The seventh front introduces late spring.

Front 11:    April 2: This is first weather system of middle spring. This front and the next three are usually  accompanied by most of April’s precipitation. Front 11 and 12 are typically the coldest of the month, the most likely to carry to snow, and the last to threaten killing frost in the South.
Front 12:     April 6: This is the last front of the spring which might bring a high only in the 20s.
Front 13:     April 11: This cold front can bring a high in the 40s, but such cold is relatively rare from now on.
Front 14:     April 16: Chances for frost are about 35 percent with this cold front, the last time this season that chances are so great.
Front 15:     April 21: Chances for cold highs in the 40s are just only ten to 15 percent with the passage of this mild front.
Front 16:    April 24: This cold front brings the last serious chance for frost to the lower Midwest – a 25 percent chance on the 25th.
Front 17:     April 28: This is the first front of late spring. The April 28th front, and the first three of May bring the last chance for snow around Yellow Springs.

April Frostwatch
Between April first and June first, around ten frosts
occur in most areas of Ohio. Chances for frost to strike after the dates listed below are:
                April l:      95%
                April 5:      90%
                April 10:     80%
                April 15:    70%
                April 20:     50%
                April 25:     40%
                April 30:     30%

WEEKLY WEATHER
WEEK ONE
    Two major weather systems, one arriving on the 2nd and another coming in on the 6th, usually dominate the first quarter of April, and these fronts bring each day of the period a 40 percent chance for precipitation.  April 3rd and April 5th are some of the wettest days of the month in the lower Midwest, carrying about a 60 and a 70 percent chance for precipitation respectively.  Snow is most likely to fall (but only ten to 20 percent of the time) on the 3rd, 4th, and 5th.  These three April days also bring an increased chance for strong winds.
There is a 20 percent chance for a high in the 80s this week all across the country’s midsection, and there is more than a 50 percent chance of an afternoon in the 60s or 70s.  Still, daily chances for frost remain steady at an average of at least 35 percent throughout the period.

WEEK TWO
    Rain is the rule for April's second quarter.  After the third major high-pressure system passes through on the 11th, however, a brief mid- April dry spell typically occurs around the 12th, chances for precipitation falling to 25 percent.  The 11th is the brightest day in the first half of April, bringing an 80 percent chance for sun, the best chances since the 7th of March.  As for temperatures, chances for highs below 50 degrees fall to less than 20 percent on the 12th where they remain until they drop to ten percent on April 22nd.  Milder highs above 60s occur better than half the time on all the days of this quarter except on the 10th, when cooler conditions typically prevail.  Frost strikes an average of 30 percent of the nights.

WEEK THREE
    The chances for a high above 50 degrees are 75 percent on almost every day during April's third quarter, and temperatures above 60 come at least half the time.  Beginning on the 20th, the chances for an afternoon high in the 70s or 80s jumps from an average of 25 percent way up to 45 percent.
    Rain or snow falls an average of 35 percent of the time this week of the year, the 15th, being the wettest day of all—carrying a 45 percent chance for rain and an additional 20 percent chance for snow. 

WEEK FOUR
    Late spring arrives this week, the warm weather creating unmistakable markers in the progress of spring. Among those landmarks:
--The 26th and the 30th record freezing temperatures less than 15 percent of the time, the first time that has happened since late September. 
--After the 22nd, chances for snow drop below five percent in most of the nation.
--Chances for a cold day in the 30s or 40s fall to only 15 percent on the 22nd; they plummet another five percent on the 26th.
    --Beginning on April 27th, highs in the 90s become possible as far north as the Great Lakes, and the chances for a high in the 80s pass the 20 percent mark at lower elevations along the 40th parallel.  The chances for a high above 70s degrees are now 50/50 or better for the first time this year.
    --April 29th and 30th are usually the mildest days this week, with the 30th bringing a 90 percent chance for highs above 60 degrees for the first time since late September.   
    --The driest days at this time of year are April 26th and 27th, each with just a 20 percent chance for rain.  The wettest days: April 29th and 30th –both carrying a 55 percent chance for precipitation.

THE DAILY WEATHER HISTORY
April 1
There is a ten percent chance for 70s today, 30 percent for 60s, another 30 percent for 50s, and another 30 percent for 40s.  Totally overcast conditions occur one day out of two, and there is a 45 percent chance for rain, 45 percent chance for frost.  Snow almost never falls on April 1st. 
April 2
This is usually the mildest and sunniest day of first week of April.  There is a 25 percent chance of temperatures in the 70s, twenty-five percent for 60s, and another 25 percent for 50s, fifteen percent for 40s, ten percent for 30s.  Rain falls a fourth of all the days, snow flurries one day in ten.  The sky is partly to mostly sunny two days out of three, and chances for frost are 45 percent.
April 3
Highs in the 70s come 25 percent of the days, 60s twenty percent, 50s ten percent, 40s thirty percent, 30s fifteen percent.  Frost occurs 40 percent of the mornings.  Rain falls 60 percent of April 3rds, and snow another ten percent.  The sun comes out just half the time.  The Great Xenia Tornado in southwestern Ohio took place on this day in 1974, and severe weather often threatens on this date.
April 4
Chilly weather with highs only in the 30s comes 20 percent of the time.  Forties occur another 20 percent, 50s thirty percent, 60s twenty percent, 70s five percent, 80s five percent.  Skies are overcast half the years, and the clouds bring rain 35 to 40 percent of the years, snow another ten percent.  Frost strikes four mornings in ten.  Beginning today, the normal average air temperatures rise one degree every three days instead of early spring’s one degree each two days.
April 5
There is a 70 percent chance for rain, plus a five to ten percent chance for snow, all of this making April 5th one of the wettest days of the month.  In spite of the odds for precipitation, however, completely overcast conditions occur only 35 percent of the time.  Highs reach the 80s five percent of the years, climb into the 70s fifteen percent, are in the 60s five percent, 50s forty percent, 40s thirty percent, and 30s five percent.  Breezy conditions seem to contribute to the low incidence of frost on the 6th: a light freeze comes just 15 percent of the mornings. 
April 6
Today begins a slight decrease in the average amount of daily cloud cover.  From now on, there is at least a 40 percent chance for sun, and most days bring a 60 to 80 percent chance.  Cool temperatures, however, are not uncommon on this date: due to the arrival of the second major high-pressure system of the month, there is a five percent chance for a high just in the 20s (the last day this spring in which 20s are likely), a 15 percent chance for 30s, twenty-five percent for 40s, twenty-five percent for 50s.  Milder 60s occur five percent of the years, and warm 70s come 25 percent.  Snow falls two years in a decade, and rain comes twice as often.
April 7
Today is typically mild, dry, and mostly sunny.  Twenty percent of the afternoons reach 70 degrees, 30 percent make it into the 60s, and another 30 percent into the 50s.  Cold 40s occur 15 percent of the time, and 30s the remaining five percent.  Skies are clear to partly cloudy 70 percent of the time.  Likelihood of rain: 30 percent, snow ten percent.  Frost comes 30 percent of the time.
April 8
Today is typically mild, dry, and mostly sunny.  Twenty percent of the afternoons reach 70 degrees, 30 percent make it into the 60s, and another 30 percent into the 50s.  Cold 40s occur 15 percent of the time, and 30s the remaining five percent.  Skies are clear to partly cloudy 70 percent of the time.  Likelihood of rain: 30 percent, snow ten percent.  Frost comes 30 percent of the time.
April 9
Today’s temperature distribution: five percent chance for highs in the 70s, thirty-five percent for 60s, twenty-five percent for 50s, fifteen percent each for 40s and 30s.This is the last day of the season on which there is a full 15 percent chance for highs just in the 30s.  There is 65 percent chance for precipitation, and snow falls more often today and on the 15th than on any other April days.  A low in the 20s is still possible 50 years in a century, but frost stays away on this date two mornings out of three. 
April 10
Highs reach into 70s five percent of April 10ths; they find 60 degrees 25 percent of the afternoons, and make it into the 50s fifty percent of the time.  Cold 40s occur fifteen percent of the days, and 30s come once in a decade or two.  The sky is often overcast on the 10th, with totally cloudy conditions occurring 40 percent of the time.  Rain is also common on this date: 40 percent of the days bring a shower, and another five percent bring a flurry.  But from now on the chance of snow decreases each day until it becomes only one in 100 by April 20th.  Frost still occurs an average of three mornings in seven. 
April 11
On average, this is the sunniest and driest day since the 21st of March, the sky being clear to partly cloudy 85 percent of the years, rain occurring only 25 percent of the years.  Highs reach into the 80s five percent of the time, into the 70s fifteen percent, into the 60s thirty-five percent, into the 50s twenty percent, and the 40s twenty-five percent.  After today, an afternoon high in the 30s becomes a rarity.  Frost, however, still occurs an average of one night in three on this date.
April 12
Thirty percent of the afternoons reach 70 degrees on this date, 20 percent make 60, forty percent 50, and just ten percent remain in the 40s.  Skies are clear to mostly sunny 65 percent of the time, and rain falls just one day in four.  Frost occurs one morning in three.  Today marks the beginning of a dramatic increase in the possibility of warm weather.  Afternoons above 70 degrees occur three times more often between the 12th and the 30th as between the 1st and the 11th. 
April 13
Chances for a high in the 70s are 20 percent today, and 60s come 40 percent of the time.  Look for cooler 50s on 25 percent of the afternoons, and for chilly 40s fifteen percent of the time.  The 13th is often cloudy, with totally overcast conditions four days in ten.  Rain falls one day out of three, but frost usually stays away, burning tender garden sprouts only one morning in five.
April 14
Rain occurs seven years in a decade on this date, making it one of the wettest days in my April weather history.  Highs reach above 70 degrees 30 percent of the time, make it into the 60s on 40 percent of the afternoons, into the 50s ten percent, and the cold 40s the remaining 20 percent.  Frost strikes just 15 percent of the mornings. 

April 15
Highs in the 70s occur 25 percent of the time, 60s come 30
percent, 50s are recorded 35 percent, and 40s occur fifteen percent.  The sky is often overcast, with two April 15ths out of three showing no sun at all.  Even though precipitation falls six days in a decade on this date, making the period of April 14th- 15th the wettest days of the month, today also marks the close of the rainiest part of April in an average year.
April 16
Highs reach into the 80s five percent of the time, into the 70s twenty-five percent, into the 60s fifteen percent, into the 50s forty percent, and into the 40s fifteen percent.  Beginning today, a major increase in the average daily amount of sunlight takes place: a rise from early April's 50/50 chance for sun or clouds up to a brighter 70 percent chance for clear to partly cloudy conditions.  Snow rarely falls on April 16th, but rain comes 35 percent of the days.  Frost strikes one morning out of every three on this date.
April 17
Today’s high temperature distribution: 15 percent chance for 70s, thirty-five percent each for 60s and 50s, ten percent for 40s, five percent for 30s.  Rain falls one day out of three; snow occurs 15 percent of the years, as does frost.  Sixty-five percent of the days bring fair to partly cloudy skies.
April 18
Today, for the first time since October 14th, there is a ten to fifteen percent chance for a high in the 80s.  Seventies come five percent of the time, 60s fifty percent of the time, 50s twenty percent, 40s five percent, 30s five percent.  The sun shines seven days in ten, rain comes four in ten, snow two in ten.  Frost burns tender plants one morning out of three (the last time this spring that odds are so strong for freezing temperatures).
April 19
Today is yet another pivot point for spring: from now on a high temperature below 40 degrees is unlikely at average elevations along the 40th Parallel until October.  Chances for highs in the 80s are five percent, for 70s thirty percent, for 60s thirty percent, for 50s twenty-five percent, for 40s ten percent.  And from this point forward, the number of frosts in any seven days declines by nearly two percent per 24 hours.  The sun shines 65 percent of the time on April 19th, and rain falls one day out of every three.

April 20
Chances for a high in the 80s surge to a full 20 percent today, the first time all spring that they have been good.  Seventies come 15 percent of the time, 60s thirty-five percent, 50s twenty percent, 40s ten percent.  The sun shines seven days out of ten; rain falls three in ten.
After the 20th, the steady advance of the year’s cold waves slows, and relatively long periods of stable, mild weather encourage the advent of full spring growth.  High temperatures almost always reach 70 at least once or twice in a week.  Spring rains often diminish, their frequency dropping at least ten percent from last week.  In fact, five years in ten, significant April precipitation is complete by the 20th.  From now on, a cold day in the 30s is virtually out of the question.  Snow falls just once or twice in a century.  Frost, however, can still be expected two or three mornings out of seven. 
April 21
Highs in the 80s come 20 percent of the days, 70s another 20 percent, 60s another 20 percent.  Fifties occur 30 percent of the time, and 40s the final ten.  The sky is overcast 40 percent of the time, and rain falls 30 percent.  Frost strikes one morning in four.
April 22
Fifteen percent of the highs today exceed 80 degrees, 15 percent are in the 70s, thirty percent in the 60s, thirty percent in the 50s, just 10 percent in the 40s.  There’s only a 15 percent chance for frost this morning.  The sky is completely overcast one day out of three.  Rain falls one day in four.  And this is the last date of the season when the chances for snow are even close to ten percent. 
April 23
There is a 15 percent chance for a high in the 80s today and a 30 percent chance for 70s, making this the first day of the year on which the high rises above 70 forty-five percent of the time.  Mild 60s occur another 45 percent of the days, with 50s coming five percent of the time, and 40s another five percent.  Rain falls one day out of four, with odds for frost the same.  The sun shines two days in three.
April 24
Fine weather is the rule for April 24th: ten percent chance for a high in the 80s, fifteen percent for 70s, fifty-five percent for 60s, twenty percent for 50s.  The sun shines 75 percent of the days, and rain comes just twice in a decade on this date.  Frost occurs only once in a decade.   
April 25
Chances for highs in the 80s are the highest so far in the year - 25 percent, and 70s occur another 25 percent, 60s yet another 25 percent.  Fifties come 20 percent, 40s five percent.  The sun shines almost 70 percent of the days; rain falls 35 to 40 percent.  There is a 25 percent chance for frost, the last time this spring that the chances are so high.
April 26
Today brings some of the best odds for sun and warmth so far this spring.  Highs rise to the 80s on 30 percent of the afternoons, to the 70s on 35 percent, making April 26th the day most likely to be warm in the first four months of the year.  Sixties occur 15 percent of the time, and cooler 50s the remaining 20 percent.  Skies are clear to partly cloudy 70 percent of the days, and rain occurs just one year out of five.  This is one of two April days on which frost almost never strikes (the 30th is the other day).
April 27
Now a day in the 90s becomes possible; and there is a 30 percent chance of a high in the 80s, and 25 percent chance for 70s.  Highs in the cooler 60s occur on another 25 percent of the afternoons; chilly 50s come 15 percent of the years, and 40s once in a decade.  Skies are mostly clear seven years in ten, and rain falls just three years in ten.  There is a 15 percent chance for frost.
April 28
The 28th is one of the cloudier days in late April, overcast more than half the time, rain falling 45 percent of the years.  The high temperature distribution: five percent chance for 80s, fifty-five percent for 70s, ten percent for 60s, twenty-five percent for 50s, five percent for 40s.  Frost comes one morning in ten.
April 29
An average April 29th brings rain five years in ten, with totally overcast conditions in the same proportion.  Temperatures in the 80s or 90s are rarely recorded today, but highs in the 70s come 45 percent of the afternoons, with 60s occurring on another 45 percent.  The remaining ten percent are in the 50s.  Frost occurs one morning in five.

April 30
Today’s high temperature distribution: 15 percent chance for 80s, forty percent for 70s, forty-five percent for 60s, and this is the first time in the year on which a high below 60 degrees is unlikely.  Chances for rain are 50 percent, but the clouds give way to sun 80 percent of the days.  Record highs in the lower Midwest begin to reach 90 degrees as April comes to a close – the first time 90s have been possible since early October.

The May Outlook

Normal temperatures continue to rise at the rate of one degree every three days this month. Average highs move from 68 on the first of May to 77 by the beginning of June. Lows climb from 45 to 56. The mean temperature for Yellow Springs May is 61.6 degrees, and it reflects conditions generally throughout the lower Midwest.

The day's length grows by 53 minutes in a Yellow Springs May, gains 25 minutes in sunrise time, 28 minutes at sunset. For all of that, the rate of the day's expansion slows by 19 minutes from April's frantic pace.

Distribution of high temperatures is normally five days in the 80s, fifteen days in the 70s, seven days in the 60s, and four days in the 50s.

The warmest May days, those with the best chance (40 percent or better chance for a day above 80 degrees) are the 11th through the 14th, the 16th, the 20th through the 22nd, the 25th, and the 31st. The coldest days in May, those with at least a 40 percent chance for highs below 70 degrees, are the 1st through the 8th, the 12th, 13th, and 15th.

In an average year, May is the second wettest month of the Yellow Springs year. Rainfall is ordinarily greatest as strawberries begin to set fruit toward the end of the month, thus the name, “Strawberry Rains.”
The cloudiest days in May, those with less than a 45 percent chance for sun, are the 5th, 12th, 25th, 26th, and 29th. The wettest May days, those with at least a 45 percent chance for precipitation, are the 12th, 18th, 19th, 22nd, 25th, 26th, 27th, and, wettest of all with a 70 percent chance for rain: the 29th.

The driest days in May, those with no more than a 30 percent chance for rain, are the 3rd, 6th, 7th, 11th, 13th and 15th. The May days with a better than an 85 percent chance for sunny or partly cloudy skies, are the 6th, 8th, 10th, 11th, 14th, 16th, 17th, 23rd, and 27th.

Springcount
Twenty-three major spring cold fronts cross the nation between the middle of February and the last week of May. Three passed through in February, seven in March, six in April.
Fronts will reach the Midwest around the following dates; they will come through about two days earlier in the West, a day or two later in the East.

Front 18: May 2nd: This front and the next two are almost always
Front 19: May 7th the coldest of the month.
Front 20: May 12th: Sometimes the weather stagnates between the May 12th front and the May 20th front, bringing on a mild heat wave.
Front 21: May 15th: This front and the next two are often
Front 22: May 20th: accompanied by the “Strawberry Rains,” the
wettest time of May.
Front 23: May 24th: This is usually the last frost-bearing front to northern gardens.

May Summercount
Between the last week of May through the first week of September, the 14 major cool fronts of summer cross the United States.

Front 1: May 29th: Summer heat typically begins several days after the arrival of this front.

WEEKLY WEATHER
WEEK ONE
This quarter of May brings highs above 60 on 75 percent of the afternoons, and warm 70s or 80s a little more than half the years. May 2nd is the coldest day of the period, bringing cool 50s on 35 percent of the afternoons and a 20 percent chance for 70s or 80s.
Frost strikes only ten to 15 percent of the mornings and is most likely after the first high-pressure system of the month passes through around the 2nd of the month and after the second system arrives near the 7th.
Each day of the period carries at least a 30 to 35 percent chance for a shower, but some of those days have a much better chance for sun than others. The 6th has an unusual 95 percent chance for clear to partly cloudy skies, making it historically one of only a handful of such days in the year. The 8th through the 10th are not all that far behind, each having an 80 to 85 percent chance for sun.

WEEK TWO
An average day in May's second quarter brings rain 25 to 40 percent of the time. The 8th, 11th and the 13th are likely to the driest of the week, the 12th and 14th the wettest. Typical highs almost always reach above 60 degrees after the 10th of May, and they rise to 70 or above at least 60 percent of the afternoons. May 11th is the day with the warmest weather history of the month: a full 50 percent of May 11ths bring temperatures in the 80s, something which doesn't happen again until the first of June. Also after the 10th of May, the chances of a killing frost drop below five percent all along the 40th parallel (except, of course, at higher elevations).

WEEK THREE
Temperatures are usually above 60 degrees this week, with the chances for 70s or better rising to 70 percent, a ten percent increase over last week's chances. Cold temperatures in the 50s occur rarely, but if they do appear, it is typically on the 21st and 24th.
Chances for frost are low, but tender plants are in some danger after the passage of May's fourth cold front on the 15th and fifth cold front on the 20th. The 18th, 19th, and 22nd are the wettest days in the period; the 20th and the 21st are the least likely to bring precipitation.

WEEK FOUR
The final week of May is historically a wet one, with completely overcast conditions more common than during any other time of the month. On the 25th, 26th and 27th, rain falls between 50 and 60 percent of the time, and the 29th is one of the rainiest days in the whole year—bringing precipitation 70 percent of the days. Average temperature distribution for this time of the month is as follows: five percent chance for highs in the 90s, 30 percent for 80s, 30 percent for 70s, 25 percent for 60s, and ten percent for 50s.
The brightest days of the week are usually the 27th and 30th, both having a 70 percent chance for sunshine. The darkest day is the 25th, which has only a 50 percent chance for a break in the clouds.

THE DAILY WEATHER HISTORY
May 1
Rain falls one May 1st out of three in my record, and odds are about the same for completely overcast conditions. Highs are in the 50s fifteen percent of the time, in the 60s fifty-five percent, in the 70s twenty-five percent, 80s five percent. Frost comes once or twice in a decade on this date.
May 2
High temperatures are in the 80s ten percent of all May 2nds, the 70s forty-five percent. Some years, a brief “Lilac Winter” strikes at this time of the month, and cooler 60s come 20 percent of the time, 50s twenty-five percent. Chances for rain are 30 percent; the sky is mostly clear better than 65 percent of all the years. Although a cool front is due today, frost this morning is rare.
May 3
Today is the May day most likely to register a high only in the 50s: forty percent of May 3rds are typically that cold. Another 40 percent are only in the 60s; and it almost never gets up to 80. Rain comes one day in three, and completely overcast conditions occur four days in ten. Frost strikes ten to fifteen percent of the mornings.
May 4
As the first cold front of the month moves over into West Virginia and Pennsylvania, high temperatures in the lower Midwest warm into the 80s twenty percent of the time and into the 70s another 20 percent. Sixties occur 45 percent of the days, and highs only reach the 50s on 15 percent of the afternoons. Rain comes one year out of three, and skies are overcast 40 percent of the time. Chances for frost are just five percent.
May 5
May 5th is generally a pleasant day, with a 25 percent chance for a high in the 80s, another 25 percent for 70s, and 50 percent for 60s. Rain falls one year in three; skies are partly to mostly sunny six years in ten; frost occurs ten to 15 percent of the mornings.
May 6
Suddenly the chances for clear to partly cloudy skies jump from the 55 percent of the last three days all the way to 90 percent. That makes May 6th one of the two sunniest days in May (the 14th is the other day). With all that blue sky, chances for 80s are 15 percent, for 70s forty percent, and for 60s twenty-five percent, leaving only 20 percent for cooler 50s. And from today forward, the chances of a day above 70 degrees are better than 50/50 for the first time since the year began. Thunderstorms often occur with the increasing likelihood for heat. Despite the fact that the skies are rarely totally overcast, showers pass through on this date one year in three
May 7
Mild to warm weather is the rule today: 25 percent of the highs reach the 80s, twenty-five percent are in the 70s, and 40 percent are in the 60s. Only ten percent remain in the cold 50s, and frost arrives just one morning out of ten. Chances for rain remain stable at 30 percent, close to the same percentage as the other days in the first week of May. Although the sun does not usually shine as much as it does on May 6th, the 7th has its share of blue skies: 70 percent of the days bring at least a few hours of sunshine.
May 8
Today's high gets above 70 on 60 percent of the years (and a third of those years are in the 80s). Mild 60s occur one day in four, and cooler 50s can be expected less than one day in five. With the arrival of the second major high-pressure system of the month, there is a slight possibility of a return of Lilac Winter
today and tomorrow, and frost has been recorded more often this morning than on any other in May: it strikes 20 percent of all the years. The sun shines 85 percent of the time, making May 8th one of the brighter days of the month. Chances for rain are only one in four, and that makes May 8th one of the two driest days of the month (the 16th is the other prime day for field and garden work).
May 9
Chances for highs in the 80s are 20 percent today, and 70s come a full 55 percent of the time. The remaining 25 percent of highs are fairly evenly divided between 60s, 50s, and 40s. Today
is the second-last day in May when a high of just 40 degrees has a ten percent chance of occurring. The final day for such odds this spring is May 25th. Skies are at least partially blue 80 percent of the time today, but a shower occurs three years in a decade. Chances for frost remain at early May's ten to 15 percent.
May 10
Today's weather is usually mild to warm, with just a 30 percent chance of rain. Highs in the 80s come 20 percent of the time, 70s come 45 percent, 60s come 35 percent. This is the first day since April 30th that chances for highs below 50 degrees are practically nil. The sun shines 85 percent of all the May 10ths in my weather history. Chances for frost: a light freeze comes once in a decade on this date, but after today, chances on a daily basis fall below five percent through the first week of June, after which they completely disappear in most areas of the United States.
May 11
Highs rise above 80 degrees 50 percent of all the afternoons on this date, making it the day with the best chance of warm weather in the entire month of May. Twenty-five percent of the days heat up to the 70s, twenty more to the 60s, and only one day in a blue moon remains in the cold 50s. The sun comes out for at least a little while on 70 percent of all May 11ths; showers are relatively rare, occurring just 20 percent of the time.
May 12
As the third major high-pressure system of the month crosses the Mississippi, today's chances for rain increase significantly over yesterday's chances. Showers occur on 45 percent of all May 12ths. Today is also one of the two cloudiest days in May: the 12th and the 25th bring completely cloudy conditions five years in a decade. Highs reach 90 ten percent of the time, warm into the 80s thirty percent, the 70s another thirty percent, the 60s twenty percent, and the 50s ten percent.
May 13
Ten percent of May 13ths rise to the 90s, thirty percent to the 80s, twenty percent to the 70s, thirty percent to the 60s, and ten percent to the 50s. Frost is rare, and this is the last time in May when the chances for rain are only 25 percent. All the remaining days bring at least 30 percent, with some going as high as 50 to 60 percent. That May period during which precipitation increases carries the name of the “Strawberry Rains,” a time during which strawberries begin to ripen in the country’s midsection and are especially vulnerable to wet conditions.
May 14
The chances for sunshine on the 14th of May are 85 percent. Rain, however, falls on 35 percent of the days. Highs in the 50s are infrequent on the 14th, occurring only once in 15 or 20 years. Temperatures climb to the 60s on 20 percent of the afternoons. Seventies are the most common, coming 45 percent of the time; 80s and 90s round out the spectrum at 25 percent and five percent, respectively.
May 15
With the arrival of the third major high-pressure system of the month, the 15th of May often brings cool temperatures. While a five-percent chance for a high in the 90s exists, the possibility for 80s drops to just ten percent. Seventies occur 50 percent of the afternoons, 60s on 30 percent, 50s on ten percent. Rain can be expected an average of once every three years on this date, with completely overcast skies more than 40 percent of the time.
May 16
A morning below 32 degrees, which could be expected atleast one day in seven around the 4th of the month, can be expected only one day in 50 on May 16th. Average highs stay inthe 70s, and typical lows come into summer-like 60s forthe first time since September. There is a 70 percent chance for a high above 70, and a 95 percent chance for a high above 60. The sun shines 85 percent of all the days. The chances for a shower are one in three. Wind is not uncommon today, as the fourth high-pressure system of the month moves across the eastern half of the nation.
May 17
Highs in the 90s are rare on the 17th and 18th of May, but 80s occur 30 percent of the afternoons; 70s come 40 percent of the time, and 60s twenty percent. Cold 50s take the remaining ten percent. Under the influence of the fourth high-pressure system of the month, skies are partly cloudy to clear today, and there is only a 15 percent chance for completely overcast conditions. Rain showers occur one day in three.
May 18
Between the 18th and the 29th, the average likelihood for precipitation grows to near 50 percent. There are a few times, however, in the next dozen days when fields may dry out a little: the 20th and 21st, the 24th, and the 28th. Today's chances are not so good: 55 percent chance for showers by nightfall. Highs in the 80s on this date come 20 percent of the time, 70s fifty percent of the time, 60s twenty-five percent, and an occasional day just in the 50s comes once every 15 years or so. Almost 40 percent of May 18ths are completely overcast.
May 19
Chances for rain are high today: 55 percent. Completely overcast skies come one year in three. Highs in the muggy 90s occur five percent of the afternoons; 80s are recorded 30 percent of the time, 70s on 30 percent of the days, 60s on 30 percent, and 50s the last five percent. As the fifth high-pressure system of the month approaches, the barometer is usually dropping, and the wind is down - conditions which typically improve prospects for fishing as well as for allergies.
May 20
Today and the 21st can offer relief from late May rains 65 percent of the time as the fifth major high-pressure system of the month moves through the Midwest. Wind speed often picks up throughout the day, and the sun shines through the cumulus clouds. Frost is not common with this fifth cold front, but morning temperatures drop into the upper 30s once in a decade below the Great Lakes. Highs reach above 80 degrees 35 percent of the afternoons, the first time chances have been so good for heat since May 16th. Mild 70s come 50 percent of the time, with highs staying in the 60s ten percent of the afternoons, and in the chilly 50s five percent. After today chances for highs in the 80s or 90s do not fall below 30 percent until middle September.
May 21
As the fifth high-pressure system of the month becomes fully entrenched, today brings a slight increase in the possibility of a high just in the 50s: ten percent of the years get that cold. Most of the time (85 percent of the time), however, May 21st is in the 70s or 80s, with 60s occurring the remaining five percent. Two years out of three, the Strawberry Rains let up on May 21st, and this date records just a 35 percent chance for showers. Skies are at least partly cloudy 70 percent of the time.
May 22
The likelihood of precipitation rises sharply to over 50 percent, but temperatures are typically mild to warm: 80s on 40 percent of the days, 35 percent in the 70s, a fourth of the days in the 60s. The sun shows through the clouds three days out of four.
May 23
The chances for rain decline from yesterday's 55 percent to 40 percent, and the likelihood for sun increases to 85 percent. Highs in the 80s come 30 percent of the time; look for 70s on 65 percent of the days, and 60s the remaining five percent.
May 24
The sixth high-pressure system of the month is due today, and statistics show some of its strength. There is a 15 percent chance for an afternoon high only in the 50s, and another five percent for 60s. Although that leaves plenty of room for warmth (80 percent chance for 70s or 80s), the risk of light frost does enter the realm of possibility for the next 72 hours. Rain on May 24th is usually light, with only 35 percent of the days bringing precipitation. Skies are mostly clear on this date three days out of four.
May 25
Even though 60 percent of May 25ths are in the 70s or 80s, a full 40 percent are not, making it the day with the most potential for chilly conditions since the 15th. A five percent chance for a high only in the 40s appears in weather history for the first time since May 9th. Fifties occur ten percent of the time, and 60s another 25 percent. Light frost is a distinct possibility this morning and tomorrow morning, and along with the increased likelihood for cold, the chances for rain rise from yesterday's 35 percent all the way to 50 percent. Clouds dominate 50 percent of the time, making today one of the two cloudiest days of the month (the 12th is the other).
May 26
Clouds and rain rule the 26th of May half the time. Highs in the 50s occur ten percent of the days, rise to the 60s on 20 percent, to the 70s on 40 percent, and to the 80s on 30 percent.
May 27
As the sixth high-pressure system of the month moves off to
the east, the likelihood for cold temperatures decreases; these forces often make the 27th one of the nicer days in late May. Although chances for rain are close to 50 percent, the sun shines through the clouds 85 percent of the time. Highs are in the 80s forty percent of the days, in the 70s on 35 percent, in the 60s twenty-five percent, and the possibility for frost is remote.
May 28
Another milestone in the progress of summer: from now through the middle of September, the chances for a day in the 90sare at least ten percent. The remaining temperature distributionfor May 28th: 80s on 40 percent of the afternoons, 70s on 15percent, 60s on 30 percent, and 50s on five percent. The arrival
of the final high-pressure system of the month increases thelikelihood for a very slight chance of frost tomorrow morning. The possibility of rain declines from yesterday's 50 percent to 35 percent, but skies are often overcast: four years in ten allow no sun to shine through.
May 29
Seventy percent of May 29ths bring precipitation. Skies are often overcast as well, with nearly half of the days bringing very little or no sun at all. Chances for 90s: ten percent, for 80s: thirty-five percent, for 70s: thirty-five percent; for 60s: fifteen percent; for 50s five percent. Lows in the 30s are possible tonight as the seventh cold front of the month moves through. In the Caribbean, hurricane season is beginning.
May 30
The likelihood of rain falls to just 35 percent today. The sun shows through the clouds 80 percent of the time instead of just 55 percent. The temperature distribution is even a little better: chances for 90s: ten percent; for 80s: thirty-five percent; for 70s: thirty-five percent; for 60s: twenty percent. Although frost does not occur frequently on this date, the seventh high-pressure system of the month can drop lows into the upper 30s.
May 31
Chances for rain are up near 40 percent today, but the sun shines seven days out of ten, and the temperature distribution covers the range between mild to hot. Highs in the 90s come ten percent of the time, 80s forty percent, 70s and 60s twenty-five percent each.