Dolores County climate

Dolores County Frost Dates and Growing Season

NOAA 1991-2020 normals for Yellow Jacket 2W, 33.1 km from Dolores County, elevation 6933 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Yellow Jacket 2W. 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 17 and the first fall freeze around October 9, a growing season of about 145 days.

Median at 36°F
last May 30, first September 30
Median at 32°F
last May 17, first October 9
Median at 28°F
last April 30, 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 13Jun 7Jun 4Jun 1May 30May 26May 22May 18May 13
32°FJun 4May 30May 24May 20May 17May 13May 8May 3Apr 29
28°FMay 22May 16May 9May 3Apr 30Apr 27Apr 23Apr 20Apr 13
24°FMay 6Apr 29Apr 24Apr 20Apr 15Apr 12Apr 7Apr 2Mar 25
20°FApr 22Apr 14Apr 7Apr 3Mar 30Mar 25Mar 18Mar 11Mar 5
16°FApr 3Mar 28Mar 19Mar 14Mar 9Mar 5Mar 1Feb 26Feb 17

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 15Sep 21Sep 24Sep 27Sep 30Oct 2Oct 5Oct 9Oct 14
32°FSep 24Sep 29Oct 2Oct 6Oct 9Oct 13Oct 16Oct 20Oct 24
28°FOct 1Oct 6Oct 11Oct 15Oct 19Oct 22Oct 26Oct 29Nov 3
24°FOct 10Oct 17Oct 22Oct 27Oct 30Nov 2Nov 5Nov 9Nov 14
20°FOct 21Oct 28Nov 1Nov 5Nov 8Nov 12Nov 15Nov 19Nov 23
16°FOct 31Nov 7Nov 11Nov 15Nov 17Nov 20Nov 24Nov 27Dec 3

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°F143137131127122118114109101
32°F169159154149145139133128119
28°F191185179174169164158152143
24°F222214207201196191183177166
20°F252242235228222217210203192
16°F278268262256250244238230218

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
6,159
Cooling degree days, base 65°F
521
Growing degree days, base 40°F
4,667
Growing degree days, base 45°F
3,531
Growing degree days, base 50°F
2,553
Growing degree days, base 55°F
1,728
Growing degree days, base 60°F
1,044

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,13500
February91400
March77006
April531052
May3018207
June59101493
July4224685
August11148603
September11039384
October4340112
November784011
December1,10600

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 33.1 km from Dolores 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 USC00059275 (Yellow Jacket 2W). Public domain.