Cimarron County climate

Cimarron County Frost Dates and Growing Season

NOAA 1991-2020 normals for Boise City 2 E, 4.3 km from Cimarron County, elevation 4133 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Boise City 2 E. 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 26 and the first fall freeze around October 17, a growing season of about 173 days.

Median at 36°F
last May 6, first October 9
Median at 32°F
last April 26, first October 17
Median at 28°F
last April 15, first October 25

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 19May 15May 11May 8May 6May 3Apr 30Apr 28Apr 23
32°FMay 9May 4May 1Apr 29Apr 26Apr 23Apr 19Apr 15Apr 10
28°FMay 1Apr 25Apr 21Apr 18Apr 15Apr 11Apr 8Apr 4Mar 30
24°FApr 21Apr 16Apr 11Apr 7Apr 3Mar 31Mar 28Mar 24Mar 16
20°FApr 10Apr 3Mar 31Mar 27Mar 23Mar 19Mar 15Mar 10Mar 4
16°FMar 30Mar 24Mar 19Mar 14Mar 11Mar 7Mar 4Feb 28Feb 21

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°FSep 26Oct 1Oct 4Oct 6Oct 9Oct 11Oct 14Oct 16Oct 21
32°FOct 4Oct 8Oct 12Oct 15Oct 17Oct 20Oct 22Oct 25Oct 29
28°FOct 13Oct 17Oct 20Oct 23Oct 25Oct 28Oct 31Nov 3Nov 7
24°FOct 21Oct 25Oct 29Nov 1Nov 3Nov 5Nov 9Nov 12Nov 17
20°FOct 29Nov 3Nov 6Nov 10Nov 13Nov 16Nov 20Nov 24Nov 29
16°FNov 5Nov 10Nov 15Nov 20Nov 23Nov 26Nov 30Dec 4Dec 10

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°F172166162158154150146142136
32°F192186181177173170166161155
28°F213206200196193189184178173
24°F234227221217212209205199192
20°F258249244238234230224219211
16°F281272266260255249244238230

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
4,405
Cooling degree days, base 65°F
1,305
Growing degree days, base 40°F
6,613
Growing degree days, base 45°F
5,224
Growing degree days, base 50°F
4,009
Growing degree days, base 55°F
2,956
Growing degree days, base 60°F
2,057

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January89604
February724013
March563171
April3229190
May11378435
June7277720
July1413877
August2347811
September37163577
October26718250
November590055
December88307

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 4.3 km from Cimarron 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 USC00340908 (Boise City 2 E). Public domain.