Forest City climate

Forest City Frost Dates and Growing Season

NOAA 1991-2020 normals for Forest City 2 Nne, 2.4 km from Forest City, elevation 1280 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Forest City 2 Nne. 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 30 and the first fall freeze around October 7, a growing season of about 159 days.

Median at 36°F
last May 8, first September 28
Median at 32°F
last April 30, first October 7
Median at 28°F
last April 18, first October 18

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

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 15Sep 20Sep 23Sep 26Sep 28Oct 1Oct 3Oct 5Oct 10
32°FSep 22Sep 28Oct 1Oct 4Oct 7Oct 9Oct 12Oct 15Oct 20
28°FOct 3Oct 8Oct 12Oct 16Oct 18Oct 21Oct 23Oct 26Oct 30
24°FOct 15Oct 19Oct 23Oct 25Oct 28Oct 30Nov 1Nov 5Nov 10
20°FOct 23Oct 29Nov 1Nov 2Nov 5Nov 7Nov 10Nov 13Nov 19
16°FNov 1Nov 4Nov 6Nov 9Nov 12Nov 15Nov 19Nov 23Nov 28

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°F159153149145143139136131124
32°F178171167163159155151146141
28°F200193188184180177172168161
24°F218212207203200196192188181
20°F238229224220216212208203196
16°F254246240236231227222217210

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
7,857
Cooling degree days, base 65°F
588
Growing degree days, base 40°F
4,540
Growing degree days, base 45°F
3,517
Growing degree days, base 50°F
2,601
Growing degree days, base 55°F
1,805
Growing degree days, base 60°F
1,129

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,57600
February1,30800
March1,040010
April595263
May25533271
June44135541
July11209663
August27147584
September16156356
October5206102
November94809
December1,37300

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 2.4 km from Forest City. 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 USC00132977 (Forest City 2 Nne). Public domain.