Carbon County climate

Carbon County Frost Dates and Growing Season

NOAA 1991-2020 normals for Saratoga 4N, 24.2 km from Carbon County, elevation 6801 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Saratoga 4N. 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 June 12 and the first fall freeze around September 7, a growing season of about 83 days.

Median at 32°F
last June 12, first September 7
Median at 28°F
last May 25, first September 16

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

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°F–––––––––
32°FAug 22Aug 28Sep 1Sep 4Sep 7Sep 10Sep 12Sep 15Sep 19
28°FSep 1Sep 7Sep 10Sep 13Sep 16Sep 19Sep 21Sep 25Sep 30
24°FSep 12Sep 16Sep 21Sep 24Sep 27Sep 30Oct 3Oct 6Oct 11
20°FSep 23Sep 27Oct 1Oct 4Oct 7Oct 11Oct 14Oct 18Oct 23
16°FOct 3Oct 9Oct 13Oct 16Oct 18Oct 22Oct 25Oct 29Nov 2

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°F807368635751453932
32°F1079994898379746758
28°F1341261211161111061019584
24°F158152146142138133129124114
20°F183176170166161157152147141
16°F208200192187183178173167160

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
8,863
Cooling degree days, base 65°F
83
Growing degree days, base 40°F
2,919
Growing degree days, base 45°F
2,044
Growing degree days, base 50°F
1,319
Growing degree days, base 55°F
744
Growing degree days, base 60°F
331

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,40100
February1,18300
March1,02600
April77608
May526069
June2269244
July5547457
August11126380
September3572141
October752019
November1,05901
December1,39200

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 24.2 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 USC00487995 (Saratoga 4N). Public domain.