Delta County climate

Delta County Frost Dates and Growing Season

NOAA 1991-2020 normals for Cedaredge 3E, 5.4 km from Delta County, elevation 6838 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Cedaredge 3E. 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 3 and the first fall freeze around October 9, a growing season of about 156 days.

Median at 36°F
last May 18, first October 2
Median at 32°F
last May 3, first October 9
Median at 28°F
last April 25, first October 19

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 4May 30May 25May 21May 18May 15May 11May 7May 1
32°FMay 21May 15May 11May 7May 3May 1Apr 29Apr 26Apr 22
28°FMay 10May 4May 1Apr 28Apr 25Apr 22Apr 18Apr 14Apr 8
24°FApr 30Apr 24Apr 19Apr 15Apr 11Apr 7Apr 4Mar 30Mar 22
20°FApr 16Apr 8Apr 3Mar 30Mar 23Mar 18Mar 14Mar 8Mar 3
16°FMar 31Mar 21Mar 15Mar 9Mar 6Mar 2Feb 28Feb 22Feb 14

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 19Sep 24Sep 27Sep 30Oct 2Oct 5Oct 7Oct 11Oct 15
32°FSep 27Oct 1Oct 4Oct 7Oct 9Oct 13Oct 16Oct 19Oct 24
28°FOct 4Oct 9Oct 13Oct 16Oct 19Oct 21Oct 25Oct 29Nov 4
24°FOct 15Oct 19Oct 23Oct 27Oct 30Nov 2Nov 6Nov 10Nov 15
20°FOct 23Oct 30Nov 3Nov 7Nov 10Nov 13Nov 17Nov 20Nov 25
16°FNov 1Nov 8Nov 12Nov 16Nov 19Nov 22Nov 25Dec 1Dec 7

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°F155149143140136131127122116
32°F177170165160156152148142135
28°F198191185181177173167162156
24°F226217210205201196191185178
20°F255247241234228222216209201
16°F282273267261256250244236225

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
6,428
Cooling degree days, base 65°F
557
Growing degree days, base 40°F
4,600
Growing degree days, base 45°F
3,506
Growing degree days, base 50°F
2,561
Growing degree days, base 55°F
1,757
Growing degree days, base 60°F
1,085

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,15500
February94500
March792010
April563052
May30013224
June66108494
July4232693
August12166618
September13138367
October486195
November82208
December1,15300

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 5.4 km from Delta 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 USC00051443 (Cedaredge 3E). Public domain.