Chaffee County climate

Chaffee County Frost Dates and Growing Season

NOAA 1991-2020 normals for Buena Vista 2S, 10.4 km from Chaffee County, elevation 7954 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Buena Vista 2S. 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 27 and the first fall freeze around September 23, a growing season of about 116 days.

Median at 36°F
last June 8, first September 13
Median at 32°F
last May 27, first September 23
Median at 28°F
last May 15, first October 2

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 21Jun 18Jun 14Jun 11Jun 8Jun 5Jun 3May 31May 26
32°FJun 11Jun 6Jun 2May 31May 27May 24May 21May 17May 13
28°FJun 1May 26May 21May 18May 15May 12May 8May 4May 1
24°FMay 18May 13May 9May 5May 3Apr 30Apr 28Apr 25Apr 19
20°FMay 7May 2Apr 29Apr 26Apr 23Apr 20Apr 16Apr 12Apr 7
16°FApr 28Apr 23Apr 18Apr 14Apr 10Apr 6Apr 3Mar 29Mar 20

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°FAug 31Sep 4Sep 7Sep 11Sep 13Sep 15Sep 18Sep 20Sep 24
32°FSep 10Sep 15Sep 18Sep 20Sep 23Sep 25Sep 27Sep 30Oct 4
28°FSep 19Sep 24Sep 27Sep 29Oct 2Oct 4Oct 6Oct 10Oct 15
24°FSep 28Oct 2Oct 6Oct 9Oct 12Oct 15Oct 18Oct 21Oct 26
20°FOct 7Oct 13Oct 16Oct 19Oct 22Oct 25Oct 28Oct 31Nov 5
16°FOct 17Oct 21Oct 25Oct 28Oct 31Nov 3Nov 6Nov 9Nov 14

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°F113106102989592888477
32°F13512912412011611310910397
28°F158150146141138133129124117
24°F180174168164160156152147140
20°F201194189185180176172167160
16°F224217211206201197192187180

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
7,521
Cooling degree days, base 65°F
131
Growing degree days, base 40°F
3,458
Growing degree days, base 45°F
2,463
Growing degree days, base 50°F
1,641
Growing degree days, base 55°F
969
Growing degree days, base 60°F
453

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,21400
February1,03300
March90501
April704011
May4321112
June14320332
July3573502
August7535425
September2493223
October601036
November91201
December1,21800

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 10.4 km from Chaffee County. Low ground, valleys and open fields freeze earlier and later than a town center or a hillside.

More

Sources

NOAA NCEI U.S. Climate Normals, 1991-2020, annual and seasonal normals for station USC00051071 (Buena Vista 2S). Public domain.