Frontier County climate

Frontier County Frost Dates and Growing Season

NOAA 1991-2020 normals for Curtis, 15.9 km from Frontier County, elevation 2606 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Curtis. 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 1 and the first fall freeze around October 9, a growing season of about 160 days.

Median at 36°F
last May 10, first October 1
Median at 32°F
last May 1, first October 9
Median at 28°F
last April 21, first October 19

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 24May 18May 15May 12May 10May 7May 5May 3Apr 28
32°FMay 13May 8May 5May 3May 1Apr 29Apr 25Apr 22Apr 17
28°FMay 4Apr 30Apr 27Apr 24Apr 21Apr 18Apr 14Apr 10Apr 5
24°FApr 24Apr 19Apr 15Apr 11Apr 8Apr 6Apr 3Mar 31Mar 24
20°FApr 15Apr 9Apr 6Apr 3Mar 31Mar 28Mar 24Mar 19Mar 14
16°FApr 7Apr 2Mar 29Mar 25Mar 22Mar 18Mar 14Mar 10Mar 5

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 18Sep 22Sep 25Sep 28Oct 1Oct 2Oct 5Oct 8Oct 12
32°FSep 25Sep 30Oct 3Oct 6Oct 9Oct 12Oct 15Oct 18Oct 22
28°FOct 4Oct 8Oct 13Oct 16Oct 19Oct 21Oct 23Oct 27Oct 31
24°FOct 15Oct 20Oct 22Oct 25Oct 27Oct 30Nov 1Nov 4Nov 8
20°FOct 21Oct 26Oct 30Nov 1Nov 4Nov 6Nov 8Nov 12Nov 16
16°FOct 28Nov 1Nov 5Nov 8Nov 11Nov 15Nov 18Nov 22Nov 27

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°F159153150146143139136131125
32°F177171167163160156152147142
28°F199193188183179176171167160
24°F219213208203199195191185179
20°F240232226221217213209203197
16°F257250245240236231225219212

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
5,859
Cooling degree days, base 65°F
1,122
Growing degree days, base 40°F
5,741
Growing degree days, base 45°F
4,543
Growing degree days, base 50°F
3,481
Growing degree days, base 55°F
2,557
Growing degree days, base 60°F
1,774

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,15801
February96004
March735138
April4326128
May18455351
June22234662
July3376838
August6314773
September90126491
October39110171
November767024
December1,11101

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 15.9 km from Frontier 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 USC00252100 (Curtis). Public domain.