La Grange climate

La Grange Frost Dates and Growing Season

NOAA 1991-2020 normals for Chicago Midway AP 3SW, 10.7 km from La Grange, elevation 620 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Chicago Midway AP 3SW. 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 10 and the first fall freeze around November 1, a growing season of about 203 days.

Median at 36°F
last April 22, first October 22
Median at 32°F
last April 10, first November 1
Median at 28°F
last April 1, first November 11

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 6May 2Apr 29Apr 26Apr 22Apr 19Apr 17Apr 14Apr 9
32°FApr 26Apr 20Apr 17Apr 14Apr 10Apr 7Apr 5Apr 2Mar 30
28°FApr 14Apr 8Apr 5Apr 3Apr 1Mar 30Mar 26Mar 21Mar 15
24°FApr 3Mar 31Mar 27Mar 24Mar 20Mar 17Mar 13Mar 9Mar 4
20°FMar 26Mar 21Mar 17Mar 13Mar 10Mar 7Mar 4Mar 1Feb 23
16°FMar 17Mar 13Mar 9Mar 6Mar 3Feb 28Feb 25Feb 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°FOct 10Oct 14Oct 17Oct 20Oct 22Oct 25Oct 27Oct 30Nov 3
32°FOct 21Oct 25Oct 28Oct 30Nov 1Nov 3Nov 6Nov 10Nov 16
28°FOct 30Nov 2Nov 5Nov 8Nov 11Nov 14Nov 18Nov 22Nov 26
24°FNov 7Nov 11Nov 15Nov 17Nov 20Nov 23Nov 27Dec 1Dec 6
20°FNov 13Nov 18Nov 22Nov 26Nov 29Dec 1Dec 5Dec 10Dec 19
16°FNov 22Nov 28Dec 1Dec 3Dec 7Dec 11Dec 16Dec 21Dec 26

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°F199194188184181177173169163
32°F224216211206203200195189183
28°F248240234229225221216212205
24°F269261255250246242237231223
20°F289280273268263259255250242
16°F304297291286281276270265259

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
5,699
Cooling degree days, base 65°F
1,161
Growing degree days, base 40°F
5,866
Growing degree days, base 45°F
4,661
Growing degree days, base 50°F
3,592
Growing degree days, base 55°F
2,654
Growing degree days, base 60°F
1,841

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,20400
February98403
March779235
April43511126
May17277379
June23231658
July1362826
August3312775
September59144536
October32321211
November679139
December1,03804

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 10.7 km from La Grange. 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 USC00111577 (Chicago Midway AP 3SW). Public domain.