Forest Lake climate

Forest Lake Frost Dates and Growing Season

NOAA 1991-2020 normals for Mundelein 4 Wsw, 5.5 km from Forest Lake, elevation 840 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Mundelein 4 Wsw. 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 29 and the first fall freeze around October 20, a growing season of about 172 days.

Median at 36°F
last May 10, first October 9
Median at 32°F
last April 29, first October 20
Median at 28°F
last April 16, first October 31

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 26May 21May 17May 13May 10May 7May 3Apr 30Apr 25
32°FMay 15May 9May 5May 2Apr 29Apr 26Apr 23Apr 18Apr 14
28°FMay 4Apr 28Apr 23Apr 19Apr 16Apr 14Apr 10Apr 6Apr 2
24°FApr 20Apr 15Apr 10Apr 6Apr 3Apr 1Mar 30Mar 26Mar 20
20°FApr 7Apr 3Mar 31Mar 29Mar 26Mar 22Mar 18Mar 15Mar 10
16°FMar 31Mar 26Mar 22Mar 18Mar 15Mar 12Mar 10Mar 6Feb 28

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 24Sep 29Oct 3Oct 6Oct 9Oct 12Oct 14Oct 18Oct 22
32°FOct 4Oct 11Oct 14Oct 17Oct 20Oct 22Oct 24Oct 28Nov 1
28°FOct 16Oct 22Oct 25Oct 28Oct 31Nov 1Nov 4Nov 7Nov 12
24°FOct 31Nov 2Nov 5Nov 7Nov 10Nov 13Nov 17Nov 20Nov 25
20°FNov 6Nov 10Nov 13Nov 17Nov 20Nov 23Nov 25Nov 29Dec 4
16°FNov 11Nov 18Nov 22Nov 25Nov 28Dec 1Dec 4Dec 8Dec 15

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°F170163158153149144141136128
32°F193186180176172168163157150
28°F216209204200196191186181172
24°F240232227222218214210206199
20°F260253247243239235230225218
16°F281272266261257253247243234

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
6,875
Cooling degree days, base 65°F
693
Growing degree days, base 40°F
4,828
Growing degree days, base 45°F
3,742
Growing degree days, base 50°F
2,783
Growing degree days, base 55°F
1,952
Growing degree days, base 60°F
1,252

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,35800
February1,13102
March931118
April566471
May26539268
June55141536
July11234688
August13193645
September12674402
October4378132
November800019
December1,18101

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 5.5 km from Forest Lake. 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 USC00115961 (Mundelein 4 Wsw). Public domain.