Park County climate

Park County Frost Dates and Growing Season

NOAA 1991-2020 normals for Wapiti 1WSW, 15.2 km from Park County, elevation 5558 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Wapiti 1WSW. 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 27 and the first fall freeze around September 25, a growing season of about 121 days.

Median at 36°F
last June 12, first September 13
Median at 32°F
last May 27, first September 25
Median at 28°F
last May 11, first October 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°FJun 26Jun 21Jun 18Jun 15Jun 12Jun 8Jun 5Jun 2May 28
32°FJun 12Jun 6Jun 2May 31May 27May 24May 20May 16May 11
28°FMay 26May 20May 17May 13May 11May 8May 5May 2Apr 27
24°FMay 14May 8May 4May 2Apr 30Apr 27Apr 23Apr 19Apr 13
20°FMay 2Apr 27Apr 22Apr 18Apr 15Apr 11Apr 7Apr 3Mar 29
16°FApr 19Apr 14Apr 10Apr 6Apr 3Mar 31Mar 27Mar 22Mar 13

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°FAug 27Sep 1Sep 6Sep 9Sep 13Sep 16Sep 20Sep 24Sep 30
32°FSep 7Sep 14Sep 19Sep 22Sep 25Sep 28Oct 1Oct 4Oct 9
28°FSep 20Sep 26Sep 30Oct 2Oct 5Oct 8Oct 13Oct 17Oct 23
24°FOct 1Oct 5Oct 9Oct 13Oct 17Oct 21Oct 25Oct 30Nov 4
20°FOct 7Oct 14Oct 19Oct 24Oct 28Nov 1Nov 4Nov 9Nov 14
16°FOct 17Oct 25Oct 29Nov 2Nov 5Nov 9Nov 12Nov 16Nov 22

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°F115107102979389858071
32°F14213412912512111711210798
28°F170161156151146142138132124
24°F193184179175171167162156149
20°F219211206201195190184177170
16°F243234228222217212206200191

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
7,509
Cooling degree days, base 65°F
229
Growing degree days, base 40°F
3,508
Growing degree days, base 45°F
2,498
Growing degree days, base 50°F
1,684
Growing degree days, base 55°F
1,043
Growing degree days, base 60°F
562

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,12700
February1,02700
March91203
April714016
May475195
June21617264
July52113527
August7082479
September26516236
October614056
November89408
December1,14400

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 15.2 km from Park 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 USC00489467 (Wapiti 1WSW). Public domain.