Chapin climate

Chapin Frost Dates and Growing Season

NOAA 1991-2020 normals for Decatur AP, 9.4 km from Chapin, elevation 675 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Decatur AP. 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 16 and the first fall freeze around October 22, a growing season of about 187 days.

Median at 36°F
last April 26, first October 11
Median at 32°F
last April 16, first October 22
Median at 28°F
last April 5, 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 12May 6May 2Apr 29Apr 26Apr 24Apr 22Apr 18Apr 13
32°FApr 30Apr 25Apr 22Apr 20Apr 16Apr 14Apr 10Apr 7Apr 3
28°FApr 21Apr 15Apr 12Apr 8Apr 5Apr 3Mar 31Mar 28Mar 20
24°FApr 10Apr 4Apr 1Mar 30Mar 27Mar 23Mar 19Mar 15Mar 8
20°FMar 31Mar 26Mar 21Mar 18Mar 15Mar 11Mar 6Mar 2Feb 25
16°FMar 22Mar 16Mar 12Mar 8Mar 5Mar 1Feb 26Feb 20Feb 13

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 26Oct 1Oct 5Oct 8Oct 11Oct 13Oct 16Oct 19Oct 23
32°FOct 7Oct 12Oct 16Oct 20Oct 22Oct 25Oct 27Oct 30Nov 3
28°FOct 21Oct 25Oct 29Oct 31Nov 2Nov 4Nov 7Nov 12Nov 17
24°FNov 1Nov 4Nov 7Nov 10Nov 14Nov 18Nov 21Nov 26Dec 1
20°FNov 8Nov 14Nov 18Nov 22Nov 27Nov 30Dec 3Dec 8Dec 14
16°FNov 16Nov 23Nov 28Dec 1Dec 5Dec 10Dec 14Dec 19Dec 24

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°F184176172169164161157152145
32°F206200195191187183178174167
28°F231223217213210206201196188
24°F256248242237232228224218212
20°F278269264259253249245239231
16°F300292285279274269264259252

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
5,393
Cooling degree days, base 65°F
1,105
Growing degree days, base 40°F
5,998
Growing degree days, base 45°F
4,755
Growing degree days, base 50°F
3,646
Growing degree days, base 55°F
2,669
Growing degree days, base 60°F
1,819

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,16502
February93506
March711351
April37013170
May12994435
June11242681
July1333797
August4273735
September66124510
October32522210
November668144
December1,00906

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 9.4 km from Chapin. 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 USW00003887 (Decatur AP). Public domain.