Chillicothe climate

Chillicothe Frost Dates and Growing Season

NOAA 1991-2020 normals for Chillicothe Mound City, 5 km from Chillicothe, elevation 650 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Chillicothe Mound City. A median date has an even chance of a later freeze in spring, or an earlier one in fall.

The last spring freeze typically comes around April 20 and the first fall freeze around October 22, a growing season of about 184 days.

Median at 36°F
last April 30, first October 10
Median at 32°F
last April 20, first October 22
Median at 28°F
last April 6, first November 2

Last freeze in spring

The chance of a later freeze than the date shown. At 10 percent, one spring in ten still freezes after the date; planting after the 10 percent date for 32°F is the cautious choice.

Threshold10%20%30%40%50%60%70%80%90%
36°FMay 17May 10May 6May 3Apr 30Apr 27Apr 24Apr 20Apr 16
32°FMay 7May 1Apr 26Apr 23Apr 20Apr 17Apr 14Apr 10Apr 6
28°FApr 22Apr 17Apr 13Apr 9Apr 6Apr 4Apr 1Mar 29Mar 25
24°FApr 9Apr 5Apr 2Mar 31Mar 29Mar 26Mar 23Mar 19Mar 14
20°FApr 1Mar 29Mar 26Mar 23Mar 20Mar 17Mar 14Mar 9Mar 2
16°FMar 26Mar 21Mar 17Mar 14Mar 11Mar 7Mar 3Feb 27Feb 19

First freeze in fall

The chance of an earlier freeze than the date shown. At 10 percent, one fall in ten freezes before the date.

Threshold10%20%30%40%50%60%70%80%90%
36°FSep 27Oct 2Oct 5Oct 8Oct 10Oct 13Oct 16Oct 19Oct 24
32°FOct 7Oct 12Oct 16Oct 18Oct 22Oct 25Oct 28Nov 1Nov 4
28°FOct 19Oct 24Oct 28Oct 31Nov 2Nov 4Nov 7Nov 11Nov 16
24°FOct 31Nov 3Nov 6Nov 10Nov 13Nov 16Nov 19Nov 24Dec 1
20°FNov 7Nov 12Nov 17Nov 21Nov 25Nov 30Dec 2Dec 6Dec 13
16°FNov 15Nov 22Nov 29Dec 2Dec 5Dec 9Dec 14Dec 19Dec 28

Growing season length

Days between the last spring and first fall freeze at each threshold, with the chance of a season at least that long.

Threshold10%20%30%40%50%60%70%80%90%
36°F182176171166162158153148140
32°F204198192188184180175169163
28°F229221216211207204200195188
24°F250243238234230225221216209
20°F274265259254249245241236228
16°F298288282276270266260252246

How often it gets that cold

The share of years with at least one night at or below each temperature.

36°F or colder
100% of years
32°F or colder
100% of years
28°F or colder
100% of years
24°F or colder
100% of years
20°F or colder
100% of years
16°F or colder
100% of years

Degree days

A degree day is one degree of the daily mean temperature beyond a base, for one day. Heating degree days count cold (the fuel a house burns), cooling degree days heat, growing degree days the warmth a crop needs; each crop has its own base.

Heating degree days, base 65°F
5,145
Cooling degree days, base 65°F
986
Growing degree days, base 40°F
5,946
Growing degree days, base 45°F
4,670
Growing degree days, base 50°F
3,538
Growing degree days, base 55°F
2,545
Growing degree days, base 60°F
1,691

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,08008
February88608
March708150
April36214178
May14270399
June17221654
July1297761
August4258719
September70106487
October31818208
November626156
December930011

What this means

NOAA computes these from the daily lows at the station over 1991-2020, fitting the dates of each year's last and first freeze to a distribution, so a date can be stated at any level of risk. 36°F is a frost risk for tender plants on a clear, calm night, since the ground cools below the air above it; 32°F is a freeze; 28°F is a hard freeze that kills most annuals.

The station is 5 km from Chillicothe. Low ground, valleys and open fields freeze earlier and later than a town center or a hillside.

More

Sources

NOAA NCEI U.S. Climate Normals, 1991-2020, annual and seasonal normals for station USC00331528 (Chillicothe Mound City). Public domain.