Spearman climate

Spearman Frost Dates and Growing Season

NOAA 1991-2020 normals for Spearman, 0.7 km from Spearman, elevation 3095 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Spearman. 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 November 4, a growing season of about 209 days.

Median at 36°F
last April 19, first October 25
Median at 32°F
last April 8, first November 4
Median at 28°F
last March 27, first November 12

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 3Apr 30Apr 26Apr 23Apr 19Apr 16Apr 12Apr 7Apr 1
32°FApr 24Apr 20Apr 15Apr 11Apr 8Apr 4Apr 1Mar 28Mar 21
28°FApr 15Apr 8Apr 4Mar 31Mar 27Mar 22Mar 17Mar 12Mar 4
24°FApr 4Mar 29Mar 23Mar 17Mar 13Mar 9Mar 4Mar 1Feb 22
20°FMar 22Mar 15Mar 9Mar 4Mar 1Feb 27Feb 21Feb 15Feb 5
16°FMar 12Mar 4Feb 28Feb 25Feb 18Feb 13Feb 7Jan 27Jan 12

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 7Oct 15Oct 19Oct 22Oct 25Oct 28Oct 31Nov 3Nov 7
32°FOct 20Oct 26Oct 30Nov 1Nov 4Nov 6Nov 9Nov 11Nov 16
28°FOct 28Nov 3Nov 6Nov 9Nov 12Nov 15Nov 17Nov 21Nov 27
24°FNov 3Nov 9Nov 14Nov 17Nov 20Nov 23Nov 26Dec 1Dec 6
20°FNov 12Nov 19Nov 23Nov 27Dec 1Dec 5Dec 9Dec 15Dec 21
16°FNov 22Nov 30Dec 5Dec 8Dec 13Dec 18Dec 23Dec 28Jan 7

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°F209201196192188184179174167
32°F232223218213209204199194187
28°F254245238233229225219213205
24°F279269262257251245239232223
20°F304295287281275269262255243
16°F337323315306301295287279267

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
99% 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
3,513
Cooling degree days, base 65°F
1,894
Growing degree days, base 40°F
7,876
Growing degree days, base 45°F
6,374
Growing degree days, base 50°F
5,024
Growing degree days, base 55°F
3,824
Growing degree days, base 60°F
2,784

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January781015
February621031
March4267151
April21435298
May55152563
June3379826
July0519984
August0475939
September19263694
October15158385
November4656122
December778016

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 0.7 km from Spearman. 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 USC00418523 (Spearman). Public domain.