Pryor climate

Pryor Frost Dates and Growing Season

NOAA 1991-2020 normals for Bridger 2 N, 31.6 km from Pryor, elevation 3583 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Bridger 2 N. 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 May 14 and the first fall freeze around September 24, a growing season of about 129 days.

Median at 36°F
last June 1, first September 12
Median at 32°F
last May 14, first September 24
Median at 28°F
last May 1, first October 4

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°FJun 17Jun 11Jun 6Jun 3Jun 1May 28May 25May 21May 16
32°FMay 30May 23May 20May 16May 14May 12May 9May 5May 2
28°FMay 13May 9May 6May 3May 1Apr 30Apr 26Apr 23Apr 19
24°FMay 2Apr 29Apr 26Apr 23Apr 20Apr 17Apr 14Apr 11Apr 6
20°FApr 24Apr 20Apr 16Apr 12Apr 10Apr 6Apr 4Apr 1Mar 25
16°FApr 16Apr 10Apr 6Apr 3Mar 31Mar 27Mar 23Mar 17Mar 11

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°FAug 31Sep 4Sep 7Sep 10Sep 12Sep 15Sep 17Sep 21Sep 25
32°FSep 7Sep 13Sep 18Sep 21Sep 24Sep 27Sep 30Oct 2Oct 7
28°FSep 20Sep 26Sep 30Oct 2Oct 4Oct 7Oct 11Oct 14Oct 19
24°FOct 1Oct 4Oct 7Oct 12Oct 16Oct 19Oct 22Oct 25Oct 31
20°FOct 8Oct 15Oct 20Oct 24Oct 28Oct 31Nov 2Nov 6Nov 12
16°FOct 18Oct 25Oct 30Nov 2Nov 6Nov 9Nov 13Nov 18Nov 22

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°F12311711110710399948983
32°F148141137133129125120115108
28°F175167162158154150146141134
24°F197191186181177172167162156
20°F221213207203199195190184177
16°F244234229224220215209203196

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
100% 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
7,414
Cooling degree days, base 65°F
414
Growing degree days, base 40°F
4,012
Growing degree days, base 45°F
2,981
Growing degree days, base 50°F
2,121
Growing degree days, base 55°F
1,407
Growing degree days, base 60°F
835

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,26600
February1,06400
March88707
April636035
May3658170
June13247370
July23182624
August45145568
September22830275
October600265
November93006
December1,23800

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 31.6 km from Pryor. 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 USC00241102 (Bridger 2 N). Public domain.