Ouray climate

Ouray Frost Dates and Growing Season

NOAA 1991-2020 normals for Ouray, 0.3 km from Ouray, elevation 7840 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Ouray. 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 1, a growing season of about 137 days.

Median at 36°F
last June 1, first September 24
Median at 32°F
last May 17, first October 1
Median at 28°F
last May 2, first October 11

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 16Jun 10Jun 7Jun 4Jun 1May 30May 26May 22May 17
32°FJun 3May 30May 24May 21May 17May 14May 11May 7May 1
28°FMay 17May 12May 8May 5May 2Apr 30Apr 27Apr 24Apr 18
24°FMay 4May 1Apr 27Apr 24Apr 21Apr 18Apr 14Apr 10Apr 5
20°FApr 25Apr 19Apr 15Apr 11Apr 8Apr 5Apr 2Mar 29Mar 21
16°FApr 14Apr 8Apr 4Mar 30Mar 26Mar 22Mar 17Mar 13Mar 7

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 9Sep 15Sep 19Sep 22Sep 24Sep 26Sep 29Oct 2Oct 6
32°FSep 19Sep 23Sep 26Sep 29Oct 1Oct 4Oct 7Oct 11Oct 16
28°FSep 27Oct 1Oct 4Oct 7Oct 11Oct 14Oct 17Oct 20Oct 24
24°FOct 5Oct 10Oct 15Oct 18Oct 22Oct 25Oct 28Oct 31Nov 5
20°FOct 15Oct 20Oct 25Oct 28Nov 1Nov 4Nov 7Nov 10Nov 16
16°FOct 24Oct 30Nov 3Nov 6Nov 10Nov 13Nov 17Nov 19Nov 23

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°F13312712211811411010610094
32°F157150146141137133128122114
28°F180173168164160156152147141
24°F203196191188183179175169161
20°F227219214209204200196191184
16°F252243237232226221217211202

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
7,684
Cooling degree days, base 65°F
117
Growing degree days, base 40°F
3,408
Growing degree days, base 45°F
2,428
Growing degree days, base 50°F
1,602
Growing degree days, base 55°F
923
Growing degree days, base 60°F
415

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,24900
February1,05000
March94401
April705016
May4281111
June16317311
July4270493
August8728406
September2493223
October601040
November93202
December1,23400

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 0.3 km from Ouray. 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 USC00056203 (Ouray). Public domain.