Altheimer climate

Altheimer Frost Dates and Growing Season

NOAA 1991-2020 normals for Pine Bluff, 18.9 km from Altheimer, elevation 230 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Pine Bluff. 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 14 and the first fall freeze around November 16, a growing season of about 245 days.

Median at 36°F
last March 29, first November 4
Median at 32°F
last March 14, first November 16
Median at 28°F
last March 4, first November 29

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 15Apr 8Apr 4Apr 1Mar 29Mar 25Mar 21Mar 17Mar 11
32°FApr 2Mar 27Mar 22Mar 18Mar 14Mar 12Mar 8Mar 4Feb 27
28°FMar 19Mar 14Mar 11Mar 7Mar 4Mar 1Feb 26Feb 20Feb 11
24°FMar 11Mar 5Mar 1Feb 25Feb 19Feb 13Feb 5Jan 29Jan 16
20°FMar 3Feb 23Feb 14Feb 7Feb 1Jan 26Jan 17Jan 7Dec 29
16°FFeb 17Feb 6Feb 1Jan 27Jan 20Jan 14Jan 11Jan 3Dec 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 23Oct 27Oct 31Nov 1Nov 4Nov 6Nov 10Nov 14Nov 20
32°FOct 31Nov 4Nov 8Nov 11Nov 16Nov 19Nov 23Nov 27Dec 1
28°FNov 9Nov 16Nov 21Nov 25Nov 29Dec 2Dec 5Dec 11Dec 20
24°FNov 21Nov 28Dec 3Dec 9Dec 16Dec 22Dec 26Jan 1Jan 11
20°FDec 4Dec 13Dec 22Dec 27Jan 1Jan 4Jan 10Jan 17Feb 2
16°FDec 13Dec 25Jan 1Jan 3Jan 8Jan 12Jan 19Jan 29Feb 7

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°F246237231226221217213208200
32°F267260255250245241236229221
28°F299289282276270265259253245
24°F336323313305300293287280266
20°F365360348340333323316307296
16°F365365365365365358348339324

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
99% of years
20°F or colder
85% of years
16°F or colder
46% 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
2,874
Cooling degree days, base 65°F
2,228
Growing degree days, base 40°F
8,684
Growing degree days, base 45°F
7,096
Growing degree days, base 50°F
5,651
Growing degree days, base 55°F
4,357
Growing degree days, base 60°F
3,216

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January700141
February533368
March35517197
April13372396
May22225668
June1422871
July05391,004
August0516981
September8323765
October12496444
November37712159
December622257

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 18.9 km from Altheimer. 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 USC00035754 (Pine Bluff). Public domain.