Sherman County climate

Sherman County Frost Dates and Growing Season

NOAA 1991-2020 normals for Stratford, 24.6 km from Sherman County, elevation 3603 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Stratford. 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 21 and the first fall freeze around October 21, a growing season of about 181 days.

Median at 36°F
last May 1, first October 13
Median at 32°F
last April 21, first October 21
Median at 28°F
last April 10, first October 30

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 14May 9May 5May 2May 1Apr 29Apr 26Apr 22Apr 18
32°FMay 3Apr 30Apr 27Apr 24Apr 21Apr 18Apr 15Apr 11Apr 6
28°FApr 27Apr 21Apr 17Apr 13Apr 10Apr 7Apr 3Mar 31Mar 24
24°FApr 16Apr 9Apr 5Apr 1Mar 30Mar 25Mar 21Mar 16Mar 10
20°FApr 4Mar 31Mar 25Mar 20Mar 16Mar 12Mar 8Mar 4Feb 28
16°FMar 25Mar 17Mar 12Mar 8Mar 5Mar 2Feb 28Feb 22Feb 14

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 1Oct 4Oct 7Oct 10Oct 13Oct 15Oct 18Oct 20Oct 23
32°FOct 8Oct 13Oct 16Oct 19Oct 21Oct 23Oct 26Oct 29Nov 1
28°FOct 17Oct 22Oct 25Oct 28Oct 30Nov 2Nov 4Nov 7Nov 12
24°FOct 26Oct 31Nov 3Nov 5Nov 8Nov 11Nov 14Nov 18Nov 23
20°FNov 2Nov 7Nov 11Nov 15Nov 18Nov 21Nov 24Nov 29Dec 3
16°FNov 7Nov 15Nov 20Nov 24Nov 27Dec 1Dec 4Dec 8Dec 13

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°F180174170166163159155151144
32°F200194189185181178174169163
28°F224215210205201197193187180
24°F245238233228224219215210201
20°F270260254249244239234227219
16°F292284277271266262256249240

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
4,481
Cooling degree days, base 65°F
1,399
Growing degree days, base 40°F
6,697
Growing degree days, base 45°F
5,322
Growing degree days, base 50°F
4,112
Growing degree days, base 55°F
3,062
Growing degree days, base 60°F
2,160

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January91104
February741014
March571276
April32113198
May11189449
June7293736
July1430894
August2371834
September43178587
October27123256
November602056
December90006

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 24.6 km from Sherman County. 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 USC00418692 (Stratford). Public domain.