Carbon County climate

Carbon County Frost Dates and Growing Season

NOAA 1991-2020 normals for Wellington 3 E, 14.2 km from Carbon County, elevation 5400 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Wellington 3 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 May 27 and the first fall freeze around September 26, a growing season of about 122 days.

Median at 36°F
last June 12, first September 17
Median at 32°F
last May 27, first September 26
Median at 28°F
last May 9, 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 29Jun 21Jun 18Jun 15Jun 12Jun 8Jun 4Jun 1May 27
32°FJun 11Jun 5Jun 2May 31May 27May 23May 19May 16May 11
28°FMay 27May 20May 15May 12May 9May 6May 3Apr 30Apr 25
24°FMay 9May 5May 1Apr 29Apr 26Apr 23Apr 20Apr 16Apr 11
20°FApr 28Apr 23Apr 19Apr 16Apr 12Apr 8Apr 5Mar 31Mar 23
16°FApr 16Apr 8Apr 4Mar 31Mar 26Mar 19Mar 13Mar 8Mar 2

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 4Sep 8Sep 11Sep 14Sep 17Sep 19Sep 21Sep 24Sep 28
32°FSep 11Sep 17Sep 21Sep 24Sep 26Sep 28Oct 1Oct 5Oct 9
28°FSep 23Sep 27Sep 30Oct 2Oct 5Oct 8Oct 12Oct 16Oct 22
24°FOct 2Oct 7Oct 12Oct 16Oct 19Oct 21Oct 25Oct 28Nov 2
20°FOct 15Oct 19Oct 23Oct 26Oct 28Nov 1Nov 3Nov 6Nov 9
16°FOct 23Oct 28Nov 1Nov 3Nov 6Nov 8Nov 11Nov 14Nov 18

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°F1181111051019793898375
32°F143136131127122118114109102
28°F169162157153149145140135128
24°F195188184179175171166161156
20°F223215208203198194190184177
16°F251243236229224219213207200

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
6,971
Cooling degree days, base 65°F
422
Growing degree days, base 40°F
4,304
Growing degree days, base 45°F
3,243
Growing degree days, base 50°F
2,328
Growing degree days, base 55°F
1,549
Growing degree days, base 60°F
907

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,33900
February1,00000
March78304
April545038
May2836209
June7162441
July3202663
August13138590
September15215320
October538060
November95501
December1,28900

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 14.2 km from Carbon 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 USC00429368 (Wellington 3 E). Public domain.