Perkins climate

Perkins Frost Dates and Growing Season

NOAA 1991-2020 normals for Stillwater 2 W, 16.9 km from Perkins, elevation 895 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Stillwater 2 W. 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 April 8 and the first fall freeze around October 27, a growing season of about 201 days.

Median at 36°F
last April 21, first October 19
Median at 32°F
last April 8, first October 27
Median at 28°F
last March 28, first November 5

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°FMay 4Apr 30Apr 27Apr 24Apr 21Apr 17Apr 13Apr 10Apr 5
32°FApr 25Apr 19Apr 15Apr 12Apr 8Apr 5Apr 1Mar 30Mar 25
28°FApr 14Apr 7Apr 3Mar 31Mar 28Mar 24Mar 19Mar 15Mar 9
24°FApr 1Mar 26Mar 20Mar 16Mar 13Mar 9Mar 5Mar 2Feb 26
20°FMar 18Mar 12Mar 8Mar 5Mar 2Feb 28Feb 24Feb 19Feb 13
16°FMar 11Mar 5Mar 1Feb 26Feb 22Feb 17Feb 11Feb 4Jan 27

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 4Oct 9Oct 13Oct 16Oct 19Oct 21Oct 24Oct 27Oct 31
32°FOct 13Oct 18Oct 21Oct 24Oct 27Oct 29Nov 1Nov 4Nov 10
28°FOct 21Oct 27Oct 30Nov 3Nov 5Nov 9Nov 12Nov 16Nov 22
24°FOct 30Nov 4Nov 8Nov 13Nov 16Nov 20Nov 23Nov 28Dec 3
20°FNov 7Nov 15Nov 21Nov 25Nov 29Dec 2Dec 6Dec 10Dec 17
16°FNov 21Nov 28Dec 3Dec 7Dec 12Dec 16Dec 21Dec 27Jan 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°F201194189185181177173168161
32°F224216211206201198194189183
28°F247239233228223218213208200
24°F272263256251246241235229219
20°F297288281276272267261254246
16°F325314307301294288283275266

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
3,817
Cooling degree days, base 65°F
1,869
Growing degree days, base 40°F
7,664
Growing degree days, base 45°F
6,210
Growing degree days, base 50°F
4,910
Growing degree days, base 55°F
3,751
Growing degree days, base 60°F
2,741

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January881010
February684126
March4768129
April21443302
May54143554
June2366814
July0515979
August0488953
September25247673
October19053346
November4855108
December806016

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 16.9 km from Perkins. 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 USC00348501 (Stillwater 2 W). Public domain.