Forest climate

Forest Frost Dates and Growing Season

NOAA 1991-2020 normals for Forest, 5 km from Forest, elevation 450 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Forest. 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 March 28 and the first fall freeze around November 2, a growing season of about 221 days.

Median at 36°F
last April 11, first October 24
Median at 32°F
last March 28, first November 2
Median at 28°F
last March 14, first November 12

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°FApr 30Apr 24Apr 19Apr 14Apr 11Apr 6Apr 2Mar 28Mar 23
32°FApr 20Apr 12Apr 6Apr 2Mar 28Mar 24Mar 20Mar 15Mar 7
28°FApr 3Mar 26Mar 22Mar 17Mar 14Mar 9Mar 3Feb 26Feb 18
24°FMar 19Mar 13Mar 8Mar 2Feb 27Feb 21Feb 15Feb 6Jan 29
20°FMar 10Mar 1Feb 22Feb 15Feb 6Jan 31Jan 27Jan 19Jan 5
16°FFeb 26Feb 13Feb 4Jan 31Jan 25Jan 18Jan 10Dec 31Dec 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°FOct 12Oct 16Oct 19Oct 22Oct 24Oct 27Oct 30Nov 2Nov 7
32°FOct 20Oct 24Oct 28Oct 31Nov 2Nov 5Nov 8Nov 12Nov 18
28°FOct 31Nov 3Nov 6Nov 9Nov 12Nov 16Nov 21Nov 25Dec 1
24°FNov 7Nov 13Nov 17Nov 22Nov 26Nov 30Dec 3Dec 9Dec 28
20°FNov 16Nov 26Dec 1Dec 4Dec 10Dec 20Dec 31Jan 5Jan 18
16°FNov 27Dec 6Dec 13Dec 24Jan 1Jan 6Jan 13Jan 24Feb 4

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°F220211206201196192187181174
32°F247237231226221215210204195
28°F276265258253247241235229220
24°F312300291284277270263256247
20°F347335328319310303295285270
16°F365365363349339333324313301

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
95% of years
16°F or colder
75% 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
2,492
Cooling degree days, base 65°F
1,895
Growing degree days, base 40°F
8,632
Growing degree days, base 45°F
6,971
Growing degree days, base 50°F
5,455
Growing degree days, base 55°F
4,103
Growing degree days, base 60°F
2,913

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January598267
February4344100
March29718229
April12263396
May22191634
June0359808
July0440905
August0432897
September6284727
October11485442
November35611165
December542584

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 km from Forest. 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 USC00223107 (Forest). Public domain.