Allendale County climate

Allendale County Frost Dates and Growing Season

NOAA 1991-2020 normals for Allendale 2 Nw, 5 km from Allendale County, elevation 180 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Allendale 2 Nw. 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 7, a growing season of about 224 days.

Median at 36°F
last April 8, first October 30
Median at 32°F
last March 28, first November 7
Median at 28°F
last March 13, first November 19

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

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 14Oct 20Oct 24Oct 27Oct 30Nov 1Nov 4Nov 7Nov 11
32°FOct 23Oct 30Nov 1Nov 4Nov 7Nov 10Nov 13Nov 18Nov 23
28°FNov 3Nov 8Nov 12Nov 16Nov 19Nov 22Nov 27Dec 2Dec 8
24°FNov 12Nov 19Nov 25Nov 30Dec 3Dec 8Dec 15Dec 25Jan 3
20°FNov 27Dec 5Dec 11Dec 20Dec 27Jan 1Jan 7Jan 16Jan 30
16°FDec 9Dec 17Dec 25Jan 1Jan 6Jan 11Jan 18Jan 28Feb 5

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°F224218213208203199194189183
32°F249241233229224220215208201
28°F281272263257252247240234224
24°F318308301293286280272264253
20°F362345335329321311304296283
16°F365365365365355347337329311

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
91% of years
16°F or colder
55% 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
2,498
Cooling degree days, base 65°F
1,930
Growing degree days, base 40°F
8,654
Growing degree days, base 45°F
6,994
Growing degree days, base 50°F
5,479
Growing degree days, base 55°F
4,125
Growing degree days, base 60°F
2,935

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January593166
February455383
March31914212
April13259382
May26192631
June1370819
July0480945
August0434899
September6274718
October10286453
November32913186
December534485

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 Allendale 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 USC00380126 (Allendale 2 Nw). Public domain.