Calhoun County climate

Calhoun County Frost Dates and Growing Season

NOAA 1991-2020 normals for Grantsville 1ESE, 7.8 km from Calhoun County, elevation 706 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Grantsville 1ESE. 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 26 and the first fall freeze around October 20, a growing season of about 175 days.

Median at 36°F
last May 4, first October 11
Median at 32°F
last April 26, first October 20
Median at 28°F
last April 15, first October 30

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 15May 10May 7May 4May 1Apr 29Apr 26Apr 22
32°FMay 10May 4May 1Apr 28Apr 26Apr 23Apr 21Apr 18Apr 15
28°FApr 29Apr 24Apr 20Apr 18Apr 15Apr 12Apr 9Apr 6Apr 2
24°FApr 17Apr 13Apr 9Apr 6Apr 4Apr 1Mar 30Mar 26Mar 21
20°FApr 6Apr 2Mar 31Mar 28Mar 25Mar 22Mar 19Mar 15Mar 9
16°FMar 30Mar 25Mar 22Mar 18Mar 15Mar 11Mar 7Mar 3Feb 24

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 1Oct 4Oct 6Oct 9Oct 11Oct 13Oct 15Oct 18Oct 22
32°FOct 8Oct 12Oct 15Oct 18Oct 20Oct 23Oct 25Oct 28Nov 1
28°FOct 16Oct 20Oct 24Oct 26Oct 30Nov 1Nov 2Nov 5Nov 10
24°FOct 26Oct 31Nov 2Nov 4Nov 7Nov 10Nov 12Nov 17Nov 24
20°FNov 4Nov 8Nov 12Nov 14Nov 17Nov 21Nov 25Nov 30Dec 4
16°FNov 11Nov 17Nov 22Nov 26Dec 1Dec 4Dec 9Dec 15Dec 23

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°F175169165161158155151146140
32°F192186182178175171168163156
28°F213207203199196192189183175
24°F236230224220215212207203198
20°F261253247242238234229224217
16°F288279272267261255249244236

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
5,062
Cooling degree days, base 65°F
947
Growing degree days, base 40°F
5,909
Growing degree days, base 45°F
4,622
Growing degree days, base 50°F
3,488
Growing degree days, base 55°F
2,500
Growing degree days, base 60°F
1,650

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,03507
February85808
March721141
April3658169
May13966399
June14185621
July1294758
August2264727
September55115511
October32514199
November633039
December91309

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 7.8 km from Calhoun County. 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 USC00463648 (Grantsville 1ESE). Public domain.