Wallace climate

Wallace Frost Dates and Growing Season

NOAA 1991-2020 normals for Wallace 1SE, 1.2 km from Wallace, elevation 35 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Wallace 1SE. 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 1 and the first fall freeze around November 7, a growing season of about 220 days.

Median at 36°F
last April 11, first October 30
Median at 32°F
last April 1, first November 7
Median at 28°F
last March 19, first November 20

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

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 17Oct 22Oct 25Oct 28Oct 30Nov 1Nov 3Nov 6Nov 10
32°FOct 26Oct 31Nov 1Nov 5Nov 7Nov 10Nov 13Nov 18Nov 25
28°FNov 3Nov 8Nov 12Nov 17Nov 20Nov 24Nov 29Dec 3Dec 12
24°FNov 16Nov 22Nov 28Dec 1Dec 5Dec 10Dec 19Dec 28Jan 5
20°FDec 1Dec 6Dec 12Dec 19Dec 27Jan 1Jan 6Jan 12Jan 22
16°FDec 8Dec 19Dec 28Jan 1Jan 6Jan 11Jan 16Jan 22Jan 30

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°F220214210205201197193188182
32°F245237231225220216211207199
28°F277267259252246240234228220
24°F313301292285278271263256245
20°F347336328320313306300290278
16°F365365357349342337332324310

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
98% of years
16°F or colder
78% 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
2,901
Cooling degree days, base 65°F
1,851
Growing degree days, base 40°F
8,262
Growing degree days, base 45°F
6,672
Growing degree days, base 50°F
5,230
Growing degree days, base 55°F
3,940
Growing degree days, base 60°F
2,812

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January684256
February536266
March39810158
April17548337
May39166592
June1351799
July0479944
August0432897
September6276720
October12072423
November36710158
December576480

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 1.2 km from Wallace. 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 USC00319026 (Wallace 1SE). Public domain.