Garfield County climate

Garfield County Frost Dates and Growing Season

NOAA 1991-2020 normals for Jordan AP, 6.3 km from Garfield County, elevation 2662 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Jordan AP. 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 18 and the first fall freeze around September 20, a growing season of about 123 days.

Median at 36°F
last May 29, first September 11
Median at 32°F
last May 18, first September 20
Median at 28°F
last May 8, first September 29

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 14Jun 7Jun 3May 31May 29May 27May 24May 20May 17
32°FMay 31May 27May 24May 21May 18May 16May 14May 11May 6
28°FMay 21May 17May 13May 11May 8May 5May 2Apr 29Apr 24
24°FMay 11May 7May 3Apr 30Apr 28Apr 25Apr 21Apr 18Apr 13
20°FMay 1Apr 26Apr 21Apr 18Apr 14Apr 11Apr 7Apr 3Mar 29
16°FApr 19Apr 14Apr 10Apr 5Apr 2Mar 30Mar 24Mar 18Mar 12

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 28Sep 2Sep 5Sep 8Sep 11Sep 13Sep 15Sep 18Sep 22
32°FSep 8Sep 13Sep 16Sep 18Sep 20Sep 22Sep 25Sep 28Oct 1
28°FSep 17Sep 21Sep 24Sep 26Sep 29Oct 1Oct 4Oct 7Oct 11
24°FSep 23Sep 27Oct 1Oct 4Oct 6Oct 10Oct 14Oct 17Oct 22
20°FOct 1Oct 6Oct 12Oct 15Oct 18Oct 20Oct 24Oct 27Nov 1
16°FOct 11Oct 17Oct 21Oct 24Oct 28Oct 31Nov 3Nov 6Nov 12

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°F12011411010610399969084
32°F140133129126123120116112106
28°F162155150147143140137133127
24°F184178172168164159155150143
20°F208200195190186182176170161
16°F231224218212207202197190184

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
8,043
Cooling degree days, base 65°F
491
Growing degree days, base 40°F
4,046
Growing degree days, base 45°F
3,048
Growing degree days, base 50°F
2,202
Growing degree days, base 55°F
1,492
Growing degree days, base 60°F
919

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,46300
February1,19400
March97506
April638031
May3638168
June11355394
July16211660
August37183611
September23032277
October637253
November1,01903
December1,35800

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 6.3 km from Garfield 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 USW00094051 (Jordan AP). Public domain.