Henryetta climate

Henryetta Frost Dates and Growing Season

NOAA 1991-2020 normals for Okemah, 29.2 km from Henryetta, elevation 935 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Okemah. 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 24 and the first fall freeze around November 9, a growing season of about 229 days.

Median at 36°F
last April 5, first November 1
Median at 32°F
last March 24, first November 9
Median at 28°F
last March 11, first November 20

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 22Apr 17Apr 12Apr 8Apr 5Apr 2Mar 30Mar 26Mar 19
32°FApr 10Apr 4Mar 31Mar 28Mar 24Mar 20Mar 16Mar 12Mar 5
28°FMar 29Mar 23Mar 18Mar 15Mar 11Mar 8Mar 4Feb 28Feb 23
24°FMar 17Mar 11Mar 8Mar 4Mar 1Feb 26Feb 22Feb 18Feb 10
20°FMar 10Mar 5Feb 28Feb 24Feb 19Feb 14Feb 9Feb 2Jan 25
16°FMar 4Feb 25Feb 18Feb 12Feb 5Jan 31Jan 25Jan 17Jan 5

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

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°F229222216212208203199193186
32°F254245240235229225219213204
28°F277269264260254249244237228
24°F304294287281277271266260250
20°F334322313307301296290281270
16°F362348341333327320311304294

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
90% 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
3,160
Cooling degree days, base 65°F
2,033
Growing degree days, base 40°F
8,306
Growing degree days, base 45°F
6,757
Growing degree days, base 50°F
5,353
Growing degree days, base 55°F
4,099
Growing degree days, base 60°F
2,991

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January775023
February573256
March36914190
April14951362
May29183619
June1385834
July0532996
August0504969
September12283721
October13273415
November4157138
December704031

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 29.2 km from Henryetta. 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 USC00346638 (Okemah). Public domain.