Routt County climate

Routt County Frost Dates and Growing Season

NOAA 1991-2020 normals for Steamboat Springs, 14.2 km from Routt County, elevation 6866 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Steamboat Springs. 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 9 and the first fall freeze around September 12, a growing season of about 93 days.

Median at 32°F
last June 9, first September 12
Median at 28°F
last May 20, first September 23

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 24Jun 18Jun 14Jun 11Jun 9Jun 6Jun 4May 31May 25
28°FJun 6Jun 1May 28May 23May 20May 16May 12May 7May 2
24°FMay 21May 14May 9May 5May 2Apr 29Apr 25Apr 20Apr 14
20°FMay 7May 1Apr 26Apr 22Apr 18Apr 14Apr 11Apr 7Apr 4
16°FApr 24Apr 19Apr 13Apr 9Apr 6Apr 3Apr 1Mar 28Mar 21

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 31Sep 4Sep 7Sep 9Sep 12Sep 14Sep 17Sep 20Sep 24
28°FSep 9Sep 14Sep 17Sep 20Sep 23Sep 26Sep 28Oct 2Oct 6
24°FSep 20Sep 24Sep 27Oct 1Oct 4Oct 6Oct 10Oct 13Oct 19
20°FSep 30Oct 4Oct 9Oct 13Oct 16Oct 19Oct 22Oct 26Oct 30
16°FOct 9Oct 16Oct 20Oct 23Oct 27Oct 31Nov 1Nov 5Nov 10

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°F837873686460565141
32°F111105101979390868275
28°F148140135130126121116110104
24°F177168164160155152147142134
20°F200192187182178174169163156
16°F224216211206202197192185177

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
8,871
Cooling degree days, base 65°F
75
Growing degree days, base 40°F
3,028
Growing degree days, base 45°F
2,119
Growing degree days, base 50°F
1,359
Growing degree days, base 55°F
752
Growing degree days, base 60°F
314

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,49100
February1,22900
March1,04800
April73408
May478079
June2284237
July6144448
August9326399
September3131170
October691018
November1,06100
December1,44600

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 14.2 km from Routt 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 USC00057936 (Steamboat Springs). Public domain.