Kemmerer Frost Dates and Growing Season

NOAA 1991-2020 normals for Kemmerer 2N, 2.8 km from Kemmerer, elevation 6937 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Kemmerer 2N. 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 8, first September 11

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 25	Jun 19	Jun 15	Jun 12	Jun 8	Jun 4	Jun 1	May 28	May 20
24°F	Jun 9	Jun 2	May 29	May 24	May 19	May 16	May 12	May 8	May 4
20°F	May 20	May 14	May 10	May 7	May 4	May 2	Apr 30	Apr 27	Apr 21
16°F	May 6	May 2	Apr 29	Apr 26	Apr 22	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 30	Sep 3	Sep 6	Sep 9	Sep 11	Sep 14	Sep 17	Sep 20	Sep 24
24°F	Sep 8	Sep 14	Sep 17	Sep 20	Sep 23	Sep 25	Sep 28	Oct 1	Oct 6
20°F	Sep 20	Sep 25	Sep 28	Oct 1	Oct 3	Oct 7	Oct 10	Oct 14	Oct 18
16°F	Oct 1	Oct 6	Oct 11	Oct 15	Oct 17	Oct 20	Oct 23	Oct 26	Oct 29

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	59	52	46	41	37	32	28	24	19
32°F	86	80	75	70	66	62	57	50	41
28°F	116	108	103	98	94	90	86	80	71
24°F	147	140	134	129	125	120	115	108	100
20°F	171	164	160	155	151	147	143	138	128
16°F	196	190	185	181	177	173	168	163	156

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: 9,695
Cooling degree days, base 65°F: 50
Growing degree days, base 40°F: 2,571
Growing degree days, base 45°F: 1,759
Growing degree days, base 50°F: 1,097
Growing degree days, base 55°F: 579
Growing degree days, base 60°F: 221

Growing degree days by month, base 50°F

Heating and cooling by month

Month	Heating DD	Cooling DD	Growing DD 50
January	1,500	0	0
February	1,303	0	0
March	1,152	0	0
April	846	0	3
May	566	0	51
June	303	3	182
July	105	32	394
August	142	15	342
September	390	0	119
October	773	0	8
November	1,128	0	0
December	1,486	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 2.8 km from Kemmerer. 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 USC00485105 (Kemmerer 2N). Public domain.