Gunnison Frost Dates and Growing Season

NOAA 1991-2020 normals for Gunnison 3SW, 4.3 km from Gunnison, elevation 7622 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Gunnison 3SW. A median date has an even chance of a later freeze in spring, or an earlier one in fall.

NOAA does not state freeze dates for this station.

Median at 28°F: last June 4, first September 17

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.

Threshold	10%	20%	30%	40%	50%	60%	70%	80%	90%
36°F	–	–	–	–	–	–	–	–	–
32°F	–	–	–	–	–	–	–	–	–
28°F	Jun 21	Jun 15	Jun 11	Jun 7	Jun 4	Jun 2	May 30	May 26	May 21
24°F	Jun 3	May 29	May 24	May 21	May 18	May 15	May 12	May 8	May 4
20°F	May 18	May 13	May 9	May 6	May 3	May 2	Apr 30	Apr 26	Apr 21
16°F	May 3	Apr 30	Apr 27	Apr 23	Apr 20	Apr 17	Apr 14	Apr 10	Apr 5

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.

Threshold	10%	20%	30%	40%	50%	60%	70%	80%	90%
36°F	–	–	–	–	–	–	–	–	–
32°F	–	–	–	–	–	–	–	–	–
28°F	Sep 5	Sep 9	Sep 12	Sep 14	Sep 17	Sep 19	Sep 21	Sep 24	Sep 27
24°F	Sep 16	Sep 20	Sep 23	Sep 25	Sep 27	Sep 29	Oct 1	Oct 3	Oct 7
20°F	Sep 26	Sep 29	Oct 1	Oct 3	Oct 5	Oct 7	Oct 10	Oct 14	Oct 18
16°F	Oct 2	Oct 5	Oct 9	Oct 12	Oct 15	Oct 18	Oct 21	Oct 24	Oct 28

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.

Threshold	10%	20%	30%	40%	50%	60%	70%	80%	90%
36°F	65	59	55	50	47	41	36	31	25
32°F	93	86	83	79	75	72	67	62	55
28°F	120	114	109	105	102	99	95	89	84
24°F	147	141	137	133	130	126	121	117	110
20°F	172	166	161	158	154	150	147	142	136
16°F	196	190	185	180	176	173	168	163	157

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: 9,935
Cooling degree days, base 65°F: 16
Growing degree days, base 40°F: 2,585
Growing degree days, base 45°F: 1,730
Growing degree days, base 50°F: 1,028
Growing degree days, base 55°F: 492
Growing degree days, base 60°F: 149

Growing degree days by month, base 50°F

Heating and cooling by month

Month	Heating DD	Cooling DD	Growing DD 50
January	1,710	0	0
February	1,385	0	0
March	1,115	0	0
April	770	0	2
May	527	0	47
June	261	1	201
July	108	11	369
August	165	4	304
September	392	0	101
October	752	0	4
November	1,136	0	0
December	1,618	0	0

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 4.3 km from Gunnison. Low ground, valleys and open fields freeze earlier and later than a town center or a hillside.

Sources

NOAA NCEI U.S. Climate Normals, 1991-2020, annual and seasonal normals for station USC00053662 (Gunnison 3SW). Public domain.