Worland climate

Worland Frost Dates and Growing Season

NOAA 1991-2020 normals for Worland, 1.2 km from Worland, elevation 4058 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 4 and the first fall freeze around October 1, a growing season of about 149 days.

Median at 36°F
last May 16, first September 22
Median at 32°F
last May 4, first October 1
Median at 28°F
last April 24, first October 13

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 29May 25May 21May 18May 16May 13May 11May 7May 4
32°FMay 18May 14May 10May 7May 4May 2Apr 30Apr 27Apr 23
28°FMay 8May 3Apr 30Apr 27Apr 24Apr 21Apr 18Apr 14Apr 10
24°FApr 27Apr 22Apr 18Apr 14Apr 11Apr 8Apr 5Apr 2Mar 28
20°FApr 17Apr 12Apr 6Apr 3Mar 31Mar 28Mar 23Mar 17Mar 12
16°FApr 9Apr 2Mar 29Mar 23Mar 18Mar 15Mar 11Mar 8Mar 4

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 9Sep 14Sep 17Sep 19Sep 22Sep 24Sep 27Sep 30Oct 3
32°FSep 21Sep 25Sep 28Sep 30Oct 1Oct 4Oct 6Oct 10Oct 15
28°FSep 30Oct 4Oct 7Oct 10Oct 13Oct 16Oct 19Oct 22Oct 25
24°FOct 10Oct 15Oct 19Oct 21Oct 24Oct 26Oct 28Oct 31Nov 4
20°FOct 19Oct 23Oct 26Oct 29Nov 1Nov 3Nov 5Nov 8Nov 12
16°FOct 26Oct 30Nov 2Nov 5Nov 7Nov 10Nov 12Nov 16Nov 20

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°F145139135132129125121116110
32°F166160156152149145142137131
28°F188182178174171167163157151
24°F212205201197193189184178172
20°F234227221217213208203198190
16°F252245240234231226220213206

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
7,671
Cooling degree days, base 65°F
661
Growing degree days, base 40°F
4,485
Growing degree days, base 45°F
3,454
Growing degree days, base 50°F
2,558
Growing degree days, base 55°F
1,800
Growing degree days, base 60°F
1,166

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,48000
February1,16700
March87406
April575149
May29017230
June73109488
July9285741
August21211656
September18238322
October577165
November1,01002
December1,41300

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 1.2 km from Worland. 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 USC00489770 (Worland). Public domain.