Calera climate

Calera Frost Dates and Growing Season

NOAA 1991-2020 normals for Durant, 9.1 km from Calera, elevation 600 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Durant. 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 31 and the first fall freeze around November 5, a growing season of about 221 days.

Median at 36°F
last April 11, first October 28
Median at 32°F
last March 31, first November 5
Median at 28°F
last March 13, first November 17

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

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 13Oct 19Oct 22Oct 26Oct 28Oct 31Nov 2Nov 5Nov 9
32°FOct 22Oct 28Oct 31Nov 2Nov 5Nov 8Nov 11Nov 17Nov 23
28°FOct 31Nov 5Nov 8Nov 12Nov 17Nov 20Nov 25Nov 29Dec 4
24°FNov 9Nov 16Nov 22Nov 26Nov 30Dec 3Dec 6Dec 12Dec 20
20°FNov 23Nov 30Dec 4Dec 8Dec 13Dec 20Dec 28Jan 4Jan 14
16°FDec 3Dec 10Dec 15Dec 22Dec 31Jan 5Jan 11Jan 21Feb 4

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°F222213208203198194190184177
32°F247237231226221216211205195
28°F275266259252247241236230220
24°F305293286280275269263256245
20°F336325318310303296290281271
16°F365357346337331325318309299

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
99% of years
16°F or colder
85% 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
2,907
Cooling degree days, base 65°F
2,182
Growing degree days, base 40°F
8,618
Growing degree days, base 45°F
7,033
Growing degree days, base 50°F
5,585
Growing degree days, base 55°F
4,293
Growing degree days, base 60°F
3,156

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January711136
February530265
March34217205
April15052359
May29191628
June1413862
July05461,011
August05501,015
September13310747
October11288447
November37212166
December647145

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 9.1 km from Calera. 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 USC00342678 (Durant). Public domain.