Ridgway climate

Ridgway Frost Dates and Growing Season

NOAA 1991-2020 normals for Ridgway, 0.5 km from Ridgway, elevation 7049 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Ridgway. 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 11 and the first fall freeze around September 13, a growing season of about 92 days.

Median at 32°F
last June 11, first September 13
Median at 28°F
last May 26, 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 30Jun 23Jun 18Jun 14Jun 11Jun 8Jun 5Jun 1May 27
28°FJun 14Jun 7Jun 3May 31May 26May 22May 19May 14May 5
24°FMay 31May 23May 17May 13May 8May 4May 1Apr 28Apr 24
20°FMay 7May 2Apr 30Apr 26Apr 23Apr 20Apr 16Apr 12Apr 7
16°FApr 25Apr 19Apr 15Apr 11Apr 9Apr 6Apr 3Mar 31Mar 22

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°FSep 1Sep 5Sep 8Sep 10Sep 13Sep 15Sep 18Sep 22Sep 25
28°FSep 10Sep 14Sep 17Sep 20Sep 23Sep 25Sep 28Oct 1Oct 4
24°FSep 19Sep 24Sep 27Sep 30Oct 2Oct 4Oct 6Oct 9Oct 14
20°FSep 29Oct 3Oct 6Oct 9Oct 13Oct 15Oct 18Oct 21Oct 26
16°FOct 9Oct 14Oct 18Oct 20Oct 23Oct 26Oct 29Nov 2Nov 6

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°F857973696460544839
32°F112105100969288847971
28°F13813112612111711310810394
24°F165159153149144141136130122
20°F191184179176172168164158151
16°F216209204200195190186181176

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
7,694
Cooling degree days, base 65°F
111
Growing degree days, base 40°F
3,395
Growing degree days, base 45°F
2,408
Growing degree days, base 50°F
1,584
Growing degree days, base 55°F
916
Growing degree days, base 60°F
412

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,29000
February1,03700
March88801
April675013
May4151116
June15515315
July3864491
August7628418
September2722202
October626027
November94401
December1,27900

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 0.5 km from Ridgway. 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 USC00057020 (Ridgway). Public domain.