Sublette County Frost Dates and Growing Season

NOAA 1991-2020 normals for Pinedale, 12.8 km from Sublette County, elevation 7210 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Pinedale. 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 5, first September 4

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 23	Jun 17	Jun 13	Jun 9	Jun 5	Jun 2	May 31	May 28	May 22
24°F	Jun 6	Jun 1	May 27	May 23	May 20	May 17	May 15	May 11	May 7
20°F	May 24	May 18	May 15	May 12	May 9	May 6	May 3	Apr 30	Apr 24
16°F	May 12	May 5	May 2	Apr 28	Apr 24	Apr 20	Apr 16	Apr 12	Apr 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.

Threshold	10%	20%	30%	40%	50%	60%	70%	80%	90%
36°F	–	–	–	–	–	–	–	–	–
32°F	–	–	–	–	–	–	–	–	–
28°F	Aug 22	Aug 26	Aug 30	Sep 1	Sep 4	Sep 6	Sep 9	Sep 12	Sep 17
24°F	Sep 2	Sep 6	Sep 10	Sep 13	Sep 16	Sep 19	Sep 23	Sep 26	Oct 1
20°F	Sep 15	Sep 20	Sep 25	Sep 27	Sep 30	Oct 3	Oct 6	Oct 11	Oct 17
16°F	Sep 28	Oct 3	Oct 6	Oct 10	Oct 14	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	48	41	36	32	28	25	22	19	16
32°F	79	73	67	62	58	54	49	43	35
28°F	110	103	97	92	88	84	79	74	68
24°F	140	132	127	122	118	114	110	104	96
20°F	165	157	152	148	144	139	135	129	122
16°F	192	185	180	176	171	167	163	158	150

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: 10,018
Cooling degree days, base 65°F: 20
Growing degree days, base 40°F: 2,364
Growing degree days, base 45°F: 1,571
Growing degree days, base 50°F: 933
Growing degree days, base 55°F: 451
Growing degree days, base 60°F: 142

Growing degree days by month, base 50°F

Heating and cooling by month

Month	Heating DD	Cooling DD	Growing DD 50
January	1,552	0	0
February	1,336	0	0
March	1,170	0	0
April	840	0	1
May	595	0	30
June	316	1	165
July	126	13	353
August	187	5	287
September	425	0	90
October	791	0	6
November	1,163	0	0
December	1,519	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 12.8 km from Sublette County. 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 USC00487260 (Pinedale). Public domain.