Wamac climate

Wamac Frost Dates and Growing Season

NOAA 1991-2020 normals for Iuka 12 Sw, 14.9 km from Wamac, elevation 590 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Iuka 12 Sw. 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 9 and the first fall freeze around October 24, a growing season of about 196 days.

Median at 36°F
last April 23, first October 14
Median at 32°F
last April 9, first October 24
Median at 28°F
last March 30, first November 2

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

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°F192185180176172168163157149
32°F216209204200196191187181175
28°F239232225221217213210205198
24°F263255249244239235229224216
20°F285277271265260256251245237
16°F306297290285280274268261254

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
4,974
Cooling degree days, base 65°F
1,251
Growing degree days, base 40°F
6,375
Growing degree days, base 45°F
5,078
Growing degree days, base 50°F
3,921
Growing degree days, base 55°F
2,899
Growing degree days, base 60°F
2,005

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,08905
February864011
March667463
April32219207
May11696448
June10256696
July1362826
August3322784
September55157553
October28335257
November616260
December950010

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 14.9 km from Wamac. 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 USC00114400 (Iuka 12 Sw). Public domain.