The October Outlook

The average number of major cold waves increases to five this month all along the 40th Parallel (there are typically only four in September, just three or four in August). These fronts bring an occasional day when the thermometer reads only in the 30s; three or four days stay in the 40s; at least a week of afternoons are in the 50s, another seven in the 60s, another seven in the 70s, and two to four in the 80s. Normal highs drop fourteen degrees, slipping from 72 to 58. Average lows move from 50 all the way down to 39.

The warmest October days, those with at least a 30 percent chance for highs above 70 degrees, are the 1st (typically the warmest day in October), 2nd, 3rd, 4th, 8th, 9th, 10th, 15th, 16th, and 31st.
The coldest days, those with at least a 50 percent chance for highs below 60 degrees, are the 20th, 22nd, 25th, 27th, 28th, and 29th.

Frost occurs at least twice in an Ohio October; and it usually strikes six nights in the next 30 (and it has been known to kill vegetables one night out of every two in the coldest years). The early mornings on which frost is most likely to occur are those of the 13th, 16th, 19th, 20th, 25th, 26th, 27th, and 29th.

October is the peak of the dry season in the Midwest. Less precipitation falls at this time of year than at any other, and the skies offer more sun than clouds. There are typically 11 completely clear days in October, eight partly cloudy, and 12 mostly cloudy or fully overcast.

The driest October days, those with only a 15 percent chance for rain, are the 26th, 28th, and 29th. The sunniest October days, those with at least a 75 percent chance for sun are the 2nd, 3rd, 5th, 6th, 7th, 8th, 10th, 13th, 14th, 15th, 28th and 29th. October’s sunniest day of all is the 15th.

The rainiest October days, those with at least a 35 percent chance for precipitation, are the 1st, 4th, 10th, 12th (the wettest day of the month), 13th, 16th, 17th, 22nd, and 23rd. Light snow falls between after the 12th two years in ten.

Autumncount
Between the first threat of frost and the first breath of winter, 18 major weather systems cross the United States. Four of those systems arrived in September; October brings at least six more:

Front 5: October 2: This front is typically a strong and consistent one, and it usually brings freezing nights to the North. The two mornings following this front are the most likely to bring a damaging freeze.

Front 6: October 4: A secondary front often comes through around the 4th of October, signaling further progress in the advent of autumn. Planting, harvest and hiking are favored for a day or two after the passage of this system.

Front 7: October 7: This front, the final one of the subseason of “early fall,” is often weaker than the weather systems of October 2nd and 4th, but frost is still to be expected in the Northeast, upper Midwest, the Plains and the Rockies. The weather following this front is typically dry and stable, but the advance of the October 13th high increases the chances for precipitation on the 10th through the 12th. Snow is not uncommon at higher elevations on those dates, and the 12th can even bring the first chance of flurries to the Ohio Valley.

Front 8: October 13: This cold front almost always brings in a chillier and more dramatic subseason of autumn known as “middle fall.” This high-pressure system can be expected to bring rain or snow and nights in the upper 20s in the North, upper 30s in the South.

Front 9: October 17: Chances for freezing temperatures continue to grow as the October fronts advance. Lows in the 20s or 30s are most likely to occur on the mornings of the 19th and 20th, with the latter date carrying the highest chances for a freeze so far this season. Chances for snow increase at the approach of a secondary system on October 20th.

Front 10: October 23: This system almost always produces rain or snow. After it passes through, however, the 26th, the 28th, and the 29th are often some of the best days of the month for harvest. But the mornings most likely to bring a killing frost during the month’s final week are the 25th and the 26th. Both have a 35 percent chance of a low only in the 20s along the 40th Parallel, the first time this season the odds have risen so high.

Front 11: October 30: When this cold front moves slowly, it brings mild winds under which to finish harvest. Between today and the arrival of early winter, there should be up to 20 days of relatively benign, dry days for fertilizing, harvesting, wood cutting, planting spring crops, raking leaves, transplanting, and digging in spring bulbs.

WEEKLY WEATHER
WEEK 1
Light frost strikes ten to 20 percent of all the nights this week, with October 3rd most likely to bring a damaging freeze in the 20s. Highs in the 80s occur on approximately ten percent of the days, and 70s can be expected 30 percent of the time. Moderate 60s dominate 50 percent of the afternoons, while colder 40s and 50s come 15 to 20 percent of the time. The likelihood for colder weather almost always increases after the 4th—after which day the chances for highs only in the 50s swells from 15 percent to 30 percent.
Rain falls about one day in three. The driest days are the 3rd, the 6th and the 7th, and the wettest days are October 1st and the 4th. Skies are clear to partly cloudy 70 percent of the time. The sunniest days are typically the 3rd and the 6th, when clouds are almost completely absent 90 percent of the time.

WEEK 2
Average temperatures have plunged six degrees in most of the nation just since the end of September. Skies remain generally clear, but the days are almost always cool. The first part of the week is generally dry, but precipitation often increases after the 8th, with the 10th bringing a 40 percent chance for rain, and the 12th a 50 percent chance. The 12th is also the first day that snow has a five to ten percent chance of falling.
Highs only in the 40s and 50s are more common this week than last, with October 11th, 12th, and 13th being the days most likely to see cold (a 40 percent chance). While some days are often warm (the 8th of October has a 40 percent chance of highs above 70 degrees), others are typically cooler (for example, the 11th of the month has only a 15 percent chance for a high above 70). The coldest morning so far in the season usually comes on October 13th, when the chances of a low in the 20s are 20 percent for the first time since spring.

WEEK 3
Lows in the 20s or 30s are most likely to occur on the mornings of the 19th and 20th, with the latter date carrying the highest chances for a freeze so far this season.
While most afternoons are in the 50s and 60s, the weather does warm up sometimes: the 15th and 16th each have a 40 percent chance for highs in the 70s or 80s, and the other days at least have a 30 percent chance of such temperatures.
Most days this week have a 30 percent chance for precipitation, with the 16th and 17th being the wettest (with a 40 percent chance). The times most likely to produce snow are the 18th through the 20th (but only five to ten percent of all the years).

WEEK 4
Highs are usually in the 50s or 60s, with the odds for 70s one in five. The danger of frost remains similar to that of the third week in October; about one night in three receives temperatures in the upper 20s or lower 30s. But by this late in the season, the chances for a hard freeze have risen past 50 percent, and the odds get better each night for killing lows.
This week is generally a brighter one than last week. Chances for sun are about 70 percent throughout the period, and some of the driest October days are the 26th, 28th, and 29th (with just a ten to fifteen percent chance for precipitation).
The sixth high-pressure system of the month usually arrives near Halloween. If it is approaching on the 31st, that evening will be warm, with maybe a little rain. If the front arrives onthe 29th or 30th, the eve of All Saints’ Day is usually unpleasant.

THE DAILY WEATHER HISTORY
October 1
The first day of October brings highs in the 80s on 25 percent of the years, 70s on 40 percent of the years (it is the last time this season that the combined possibility for 70s and 80s reaches so high), 60s on 25 percent, 50s on 15 percent. Skies are completely overcast and rain occurs 40 percent of the days. Nighttime lows are in the mild 50s or 60s more than half the time, and frost comes only once in a decade.
October 2
The 2nd of October warms to the lower 80s twenty-five percent of the afternoons and to the 70s fifteen percent, a significant decline from yesterday's possibilities. Highs get into the 60s fifty percent of the time and into the 50s ten percent of the time. Sky conditions are usually less cloudy than on the 1st, and 80 percent of the days are partly sunny. Rain occurs one day in three. Half the nighttime lows fall below 60 degrees, but frost is rare on this date.
October 3
For the first time since May 9th there is a 25 percent chance for a high only in the 50s. On the other hand, 30 percent of the days rise to the 60s, thirty percent to the 70s, and 15 percent to the 80s. The sky is clear to partly cloudy 90 percent of the time, and rain occurs just one day in four. Morning lows in the 20s become slightly more frequent after this date, and lows below 50 degrees now occur 60 percent of the time.
October 4
Highs in the 80s come 15 percent of the time, in the 70s twenty-five percent, in the 60s forty percent, in the 50s fifteen percent. And for the first time since early May, an afternoon in the 40s becomes possible. Rain occurs 50 percent of all the days, the second highest percentage of the month. Frost strikes one morning in four, the highest odds until the 13th. A little more than half the nighttime lows reach below 50 degrees.
October 5
There is a fifteen percent chance for highs in the 80s today, and fifteen percent for 70s. Sixties occur 30 percent of the afternoons, fifties 40 percent (the first time the chances for 50s have been so high since May 3rd). The sky is clear to mostly sunny 80 percent of the years, with rain coming one year in three. Frost occurs 15 percent of the mornings, and lows fall to the 30s thirty-five percent of the years, the first time that percentage has been so high this fall.
October 6
Completely cloudy conditions are rare today. The 6th is one of the two sunniest days of the month (the other is the 8th), bringing only one day in ten without at least some blue sky. Today’s high temperature distribution: ten percent chance for 80s, fifteen percent for 70s, forty-five percent for 60s, and thirty percent for 50s. Showers occur twice in a decade. Lows drop below 50 on 70 percent of the nights. And one more pivotal step to winter: for the first time in the autumn, the chances of a morning in the 20s rise to 15 percent.
October 7
Overcast skies come 30 percent of October 7ths, but rain continues at yesterday's light 20 percent. Seventy-degree afternoons are observed 25 percent of the time, 60s thirty percent, 50s forty percent, and 40s five percent. Only five percent of the mornings are above 60 degrees; only 15 percent are even above 50. Frost strikes one day in five.
October 8
Chances for rain continue at a low 20 percent today. Chances for completely overcast condition are also just 20 percent. The high temperature distribution is as follows: 80s fifteen percent of the time, 70s thirty percent, 60s thirty percent, and 50s twenty-five percent. Frost comes one day in five.
October 9
The 9th and the 10th are the last two days of the year on which there is an 85 percent chance for a high temperature above 60 degrees (45 percent chance for 60s, forty percent for 70s). A ten percent chance remains for cool 50s, five percent for an afternoon only in the 40s. The sky is partly to mostly sunny 65 percent of the days; showers occur 35 percent of the time. In spite of the mild temperatures, today is the earliest day for snow in the lower Midwest. Frost comes 15 percent of the mornings, and nighttime lows drop below 50 half the time.
October 10
There is a ten percent chance for a high in the 80s today, 30 percent for 70s, forty-five percent for 60s, fifteen percent for 50s. The frequency of showers is one day in three, and totally overcast conditions occur 25 percent of the time. Seventy percent of the mornings fall below 50 degrees, and frost strikes 15 percent of the time.
October 11
The milder temperatures of the 9th and 10th give way on the 11th: only 15 percent of today’s afternoons reach 70. Fifty-five percent are in the 60s, fifteen percent are in the 50s; and, for the first time since April 20th, there is a 15 percent chance for highs just in the 40s. Frost occurs one morning in 15. Showers fall, and clouds cover the sky one day in three. Lows drop below 50 two nights in three.
October 12
Today and the 21st are the two October days most likely to
bring clouds – completely overcast conditions occurring half the time. Rain is also likely – showers or all-day drizzle occurring six days in ten. And the first flurries of the Ohio season sometimes fall on this date. Highs warm to the 80s five percent of the days, to the 70s fifteen percent, to the 60s thirty percent, 50s forty percent, and 40s ten percent.
October 13
Frost occurs this morning 40 percent of all the years in my records, the highest percentage so far this fall. Twenty-five percent of those freezing temperatures are in the 20s, so this is the first really dangerous day of the year for tender garden vegetables. Daytime highs rise into the 80s fifteen percent of the years, but that is the last time for such a percentage until April 20th. Chances for 70s are 15 percent, for 60s fifteen percent, for 50s forty percent, for 40s five percent. Rain: one day in three; skies are clear to partly cloudy 80 percent of the time.
October 14
Today is sunny to partly cloudy eight days in ten. Mild conditions usually prevail, with highs above 70 fifteen percent of the afternoons, 60s occurring about half the time, 50s a fourth of the time, and 40s just once in 15 years. Even though nights are ordinarily in the 30s and 40s, frost comes only one morning in ten on this date. Showers occur one day in three.
October 15
The 15th is usually pleasant, with clear to partly cloudy conditions prevailing 90 percent of the days. Rain passes through just one day in four. Highs in the 80s occur five percent of the time, 70s thirty percent, 60s forty percent, 50s twenty-five percent. Morning lows reach the 30s or 40s half the years, and frost strikes one to two dawns out of ten.
October 16
Today's weather statistics are very similar to those of the 15th, with highs in the 80s coming five percent of the time, 70s thirty percent, 60s thirty-five percent, and 50s thirty percent. The likelihood for clouds and rain increases slightly: showers fall 30 percent of the days; the sun shines 70 percent of the time. Frost strikes 15 percent of the nights, but only half those frosts are hard.
October 17
There is a 25 percent chance for highs in the 70s today, 50 percent for 60s, and another 25 percent for 50s. Skies are totally overcast, and rain is recorded 40 percent of the time. A 15 percent chance exists that lows will reach the 30s, ten percent for a freeze in the 20s.
October 18
There is a 30 percent chance for highs in the 70s today. Sixties come another 30 percent, 50s twenty-five percent, and cold 40s fifteen percent. The sky is overcast 40 percent of the time, and rain falls 25 percent. From the 18th through the 20th, for the first time since the middle of April, there is a steady ten percent chance for snow flurries. Frost strikes one night in five on this date.
October 19
For the first time since April 18th, there is a five percent chance for high temperatures only in the 30s. Chances for low temperatures in the 30s jump above 50 percent. Highs are in the 70s thirty percent of the afternoons, in the 60s twenty-five percent, in the 50s thirty percent, in the 40s ten percent. Showers and overcast skies can be expected one day in three; flurries occur just once in a decade.
October 20
Today is often one of the cooler days of October, with a 40 percent chance of overcast skies, and a 30 percent chance for rain or light snow. Highs climb above 70 only five percent of the time (the first time odds for heat have been so low since April 11th). Most afternoons reach the 60s (a 40 percent chance) or the 50s (there’s a 45 percent chance or that). There is also a five percent chance for 30s. A light frost strikes most gardens five years in ten, the highest likelihood so far this fall.
October 21
Today and the 12th are the two October days most likely to bring clouds: 45 percent of the days are completely overcast, 30 percent carry rain. One in ten afternoons has a high above 80, twenty-five percent of the days are in the 70s, twenty-five percent in the 60s, twenty percent in the 50s, twenty percent in the 40s. Frost comes one morning in five, lows in the 20s one morning in 20.
October 22
Today is the last day of the year on which there is a ten percent chance of a high in the 80s. From now on, temperatures remain below that mark at least until the first week of April. Highs come into the 70s fifteen percent of the days, into the 60s twenty-five percent, into the 50s forty-five percent, and into the 40s five percent. Chances for rain are 40 percent; overcast conditions occur four to five days in a decade. Frost strikes one morning in five.

October 23
Another step towards winter: from now on, the chances for high below 50 degrees jump to 30 percent for the first time since April 9th. But afternoons still warm to the 70s twenty-five percent of the time, to the 60s thirty percent, to the 50s fifteen percent. Skies are overcast, and rain comes four times in a decade on this day. Frost occurs 20 percent of the mornings.
October 24
Today’s chances for precipitation: 25 percent. Highs are in the 70s twenty-five percent of the years, in the 60s forty percent, in the 50s fifteen percent, in the 40s fifteen percent, in the 30s five percent. Sixty percent of the days are clear to partly cloudy. Light frost occurs one morning in three or four.
October 25
Today brings one more statistical movement towards winter as the chances for a morning freeze in the 20s rises to 40 percent for the first time since late March; and today and the 26th are the two October days most likely to bring a hard freeze. Highs in the 70s occur 15 percent of the years; there's a 30 percent chance of 60s, 25 percent chance for 50s, twenty percent chance for 40s, ten percent for 30s. Rain or snow comes 45 percent of the days. Skies are completely overcast four days in ten.
October 26
Today’s chances for morning frost are 55 percent, and the likelihood of rain is only 15 percent. The temperature distribution: 25 percent chance for highs in the 70s, thirty percent for 60s, fifteen percent for 50s, twenty-five percent for 40s, and five percent for 30s. Completely overcast conditions occur four days in ten.
October 27
Chances for frost are 45 percent, for rain 30 percent, for totally overcast skies 55 percent, for highs in the 70s twenty-five percent, for 60s fifteen percent, for 50s fifty percent, for 40s ten percent.
October 28
The period between October 28th and November 1st is the best time remaining in the year for late harvest and outdoor activities. The sun shines more often these days than on any others for the rest of the year. October 28th is usually the driest of all those days, with the chance for rain dropping to only ten percent. Skies are clear to partly cloudy 80 percent of the time. Temperature distribution is almost identical to that of yesterday: 25 percent chance for 70s, fifteen percent for 60s, fifty percent for 50s, and ten percent for 30s. Chances for frost fall slightly to 30 percent.
October 29
The likelihood for sun rises to 85 percent today, and rain comes only once or twice in a decade. Frost occurs 60 percent of the mornings. Highs in the 70s occur 15 percent of the afternoons, 60s forty percent of the time, 50s thirty percent, 40s fifteen percent.
October 30
Chances for a day in the 70s double over those of yesterday to a full 30 percent. Sixties can be expected on another 30 percent of the afternoons, 50s on another 30 percent; ten percent chance for 40s. Half the mornings bring frost, and skies are clear 80 percent of the time; rain occurs on just 15 percent of the days. Between today and April 14th, there is a possibility of a low temperature below 20 degrees.
October 31
The 31st is typically a fine day, with temperatures in the 70s forty percent of the time, highs in the 60s another 40 percent, 50s coming the remaining 20 percent. Rain or snow falls just one year in five. Skies are mostly sunny 80 percent of the days, and frost occurs on only 25 percent of the mornings.
Frostwatch
The following chart shows the chances that frost will have struck your plants by the date indicated. Calculations are based on average frequency of freezing temperatures in central Ohio during the month of October. Adjust by adding five percent if you live in the northern part of the state. Subtract five percent in southern counties. There is an average of six frosts in central Ohio during the month.

Date Chance for Light Frost Chance for Killing Frost at Average Elevations Along the 40th Parallel

October 1: 85 percent 10 percent
October 5: 90 percent 13 percent
October 10: 100 percent 20 percent
October 15: 30 percent
October 20: 40 percent
October 25: 60 percent
October 30: 80 percent

October