Champaign climate

Champaign Frost Dates and Growing Season

NOAA 1991-2020 normals for Champaign 3S, 3.6 km from Champaign, elevation 721 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Champaign 3S. 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 15 and the first fall freeze around October 24, a growing season of about 190 days.

Median at 36°F
last April 26, first October 15
Median at 32°F
last April 15, first October 24
Median at 28°F
last April 4, 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 10May 5May 2Apr 30Apr 26Apr 23Apr 20Apr 17Apr 12
32°FApr 29Apr 24Apr 21Apr 18Apr 15Apr 12Apr 8Apr 5Apr 1
28°FApr 19Apr 14Apr 10Apr 6Apr 4Apr 1Mar 30Mar 26Mar 20
24°FApr 9Apr 4Mar 31Mar 29Mar 25Mar 22Mar 18Mar 14Mar 9
20°FMar 31Mar 26Mar 22Mar 18Mar 15Mar 12Mar 9Mar 4Feb 27
16°FMar 23Mar 18Mar 14Mar 10Mar 8Mar 4Mar 1Feb 25Feb 17

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°FOct 1Oct 6Oct 9Oct 12Oct 15Oct 17Oct 19Oct 22Oct 26
32°FOct 11Oct 16Oct 19Oct 22Oct 24Oct 26Oct 29Oct 31Nov 5
28°FOct 22Oct 26Oct 29Oct 31Nov 2Nov 4Nov 8Nov 11Nov 16
24°FNov 1Nov 4Nov 7Nov 10Nov 12Nov 15Nov 18Nov 22Nov 27
20°FNov 7Nov 12Nov 15Nov 19Nov 22Nov 25Nov 29Dec 1Dec 8
16°FNov 14Nov 20Nov 25Nov 28Dec 1Dec 4Dec 8Dec 13Dec 20

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°F189182177173169165161157150
32°F209202198194190186182177171
28°F230224219215211207203199193
24°F254247242237233228224219213
20°F275267261256252247243237230
16°F295286280275269264259253246

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
5,657
Cooling degree days, base 65°F
1,073
Growing degree days, base 40°F
5,860
Growing degree days, base 45°F
4,649
Growing degree days, base 50°F
3,568
Growing degree days, base 55°F
2,609
Growing degree days, base 60°F
1,774

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,21801
February98504
March752141
April3889152
May13884417
June14236672
July1317781
August3276738
September64130518
October33419205
November707035
December1,05204

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 3.6 km from Champaign. Low ground, valleys and open fields freeze earlier and later than a town center or a hillside.

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Sources

NOAA NCEI U.S. Climate Normals, 1991-2020, annual and seasonal normals for station USC00118740 (Champaign 3S). Public domain.