Tolono climate

Tolono Frost Dates and Growing Season

NOAA 1991-2020 normals for Champaign Willard AP, 6.2 km from Tolono, elevation 754 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Champaign Willard 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 19 and the first fall freeze around October 17, a growing season of about 180 days.

Median at 36°F
last April 30, first October 8
Median at 32°F
last April 19, first October 17
Median at 28°F
last April 8, first October 28

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 15May 10May 6May 3Apr 30Apr 27Apr 24Apr 21Apr 17
32°FMay 5Apr 30Apr 26Apr 22Apr 19Apr 17Apr 14Apr 10Apr 6
28°FApr 24Apr 18Apr 14Apr 11Apr 8Apr 5Apr 3Mar 31Mar 26
24°FApr 13Apr 7Apr 3Apr 1Mar 30Mar 26Mar 22Mar 17Mar 10
20°FApr 4Mar 31Mar 27Mar 23Mar 19Mar 15Mar 11Mar 7Mar 1
16°FMar 27Mar 20Mar 16Mar 12Mar 9Mar 6Mar 2Feb 27Feb 18

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 23Sep 28Oct 2Oct 5Oct 8Oct 11Oct 14Oct 17Oct 22
32°FOct 3Oct 8Oct 12Oct 15Oct 17Oct 20Oct 23Oct 26Oct 31
28°FOct 15Oct 19Oct 23Oct 25Oct 28Oct 30Nov 1Nov 5Nov 11
24°FOct 27Oct 31Nov 2Nov 5Nov 8Nov 11Nov 14Nov 19Nov 25
20°FNov 5Nov 8Nov 12Nov 15Nov 19Nov 22Nov 26Dec 1Dec 7
16°FNov 10Nov 16Nov 21Nov 25Nov 29Dec 2Dec 6Dec 12Dec 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°F178173167163159155151146139
32°F199194189184180175171166159
28°F220213208204201196192187181
24°F246238233228223219214209201
20°F271262255249245241236229222
16°F291281274270265260254247240

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
5,586
Cooling degree days, base 65°F
1,054
Growing degree days, base 40°F
5,882
Growing degree days, base 45°F
4,663
Growing degree days, base 50°F
3,574
Growing degree days, base 55°F
2,607
Growing degree days, base 60°F
1,763

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,20902
February97105
March737348
April37812165
May13299438
June13241678
July2303766
August5247707
September66124510
October33626212
November695138
December1,04306

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 6.2 km from Tolono. 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 USW00094870 (Champaign Willard AP). Public domain.