Simpson climate

Simpson Frost Dates and Growing Season

NOAA 1991-2020 normals for Ft Polk Fullerton Lndg Strip, 11.6 km from Simpson, elevation 310 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Ft Polk Fullerton Lndg Strip. 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 1 and the first fall freeze around November 23, a growing season of about 268 days.

Median at 36°F
last March 15, first November 11
Median at 32°F
last March 1, first November 23
Median at 28°F
last February 7, first December 10

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 5Mar 31Mar 25Mar 19Mar 15Mar 11Mar 6Mar 1Feb 23
32°FMar 24Mar 16Mar 10Mar 5Mar 1Feb 26Feb 20Feb 12Jan 31
28°FMar 9Mar 2Feb 25Feb 16Feb 7Jan 31Jan 26Jan 16Jan 2
24°FFeb 28Feb 15Feb 5Jan 30Jan 23Jan 17Jan 11Jan 2Dec 22
20°FFeb 9Feb 1Jan 29Jan 22Jan 16Jan 9Jan 5Dec 31Dec 21
16°F–––––––––

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 28Nov 1Nov 5Nov 8Nov 11Nov 14Nov 18Nov 23Dec 1
32°FNov 4Nov 10Nov 15Nov 19Nov 23Nov 27Dec 1Dec 7Dec 20
28°FNov 15Nov 24Nov 29Dec 4Dec 10Dec 18Dec 28Jan 5Jan 14
24°FNov 30Dec 9Dec 19Dec 27Jan 1Jan 5Jan 12Jan 19Feb 2
20°FDec 15Dec 26Jan 1Jan 3Jan 7Jan 12Jan 19Jan 30Feb 4
16°F–––––––––

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°F271259253247242237230223215
32°F307294285276268262255249238
28°F345333324316308300291281265
24°F365365365357347339331319303
20°F365365365365365365365360342
16°F365365365365365365365365365

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
96% of years
24°F or colder
71% of years
20°F or colder
28% of years
16°F or colder
5% 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
1,751
Cooling degree days, base 65°F
2,706
Growing degree days, base 40°F
10,114
Growing degree days, base 45°F
8,376
Growing degree days, base 50°F
6,745
Growing degree days, base 55°F
5,241
Growing degree days, base 60°F
3,891

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January4489135
February32917175
March18747341
April56123518
May5314775
June0478928
July05611,026
August05531,018
September1392841
October54165577
November24232266
December43114146

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 11.6 km from Simpson. 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 USW00053988 (Ft Polk Fullerton Lndg Strip). Public domain.