Washakie County climate

Washakie County Frost Dates and Growing Season

NOAA 1991-2020 normals for Worland, 22.5 km from Washakie County, elevation 4172 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Worland. 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 13 and the first fall freeze around September 26, a growing season of about 133 days.

Median at 36°F
last May 30, first September 16
Median at 32°F
last May 13, first September 26
Median at 28°F
last May 1, 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 13Jun 7Jun 4Jun 1May 30May 26May 22May 19May 15
32°FMay 27May 22May 18May 15May 13May 10May 8May 5May 2
28°FMay 15May 10May 7May 3May 1Apr 30Apr 27Apr 23Apr 19
24°FMay 3Apr 30Apr 27Apr 23Apr 21Apr 18Apr 16Apr 12Apr 7
20°FApr 24Apr 20Apr 15Apr 12Apr 9Apr 5Apr 2Mar 30Mar 21
16°FApr 17Apr 12Apr 7Apr 2Mar 30Mar 25Mar 20Mar 14Mar 9

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 2Sep 8Sep 11Sep 13Sep 16Sep 18Sep 20Sep 23Sep 28
32°FSep 14Sep 18Sep 21Sep 24Sep 26Sep 28Oct 1Oct 3Oct 7
28°FSep 23Sep 27Sep 30Oct 2Oct 5Oct 7Oct 10Oct 13Oct 17
24°FOct 2Oct 6Oct 9Oct 13Oct 15Oct 18Oct 20Oct 22Oct 26
20°FOct 9Oct 15Oct 18Oct 20Oct 23Oct 25Oct 28Oct 31Nov 4
16°FOct 18Oct 22Oct 25Oct 28Oct 31Nov 2Nov 5Nov 8Nov 11

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°F1261191161121081051019790
32°F151144140136133129125121117
28°F172167162158154151147143137
24°F193188183179175172169164158
20°F218209204200196191187182174
16°F237229224219215210205199191

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
7,946
Cooling degree days, base 65°F
528
Growing degree days, base 40°F
4,200
Growing degree days, base 45°F
3,194
Growing degree days, base 50°F
2,329
Growing degree days, base 55°F
1,600
Growing degree days, base 60°F
998

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,49300
February1,18700
March88807
April603037
May3259194
June9179441
July11234688
August27175614
September20231298
October621150
November1,04701
December1,45200

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 22.5 km from Washakie County. Low ground, valleys and open fields freeze earlier and later than a town center or a hillside.

More

Sources

NOAA NCEI U.S. Climate Normals, 1991-2020, annual and seasonal normals for station USW00024062 (Worland). Public domain.