Caribou County Frost Dates and Growing Season

NOAA 1991-2020 normals for Soda Springs AP, 13.4 km from Caribou County, elevation 5842 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Soda Springs AP. 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 May 27, first September 12

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 12	Jun 6	Jun 1	May 27	May 22	May 18	May 14	May 7
24°F	May 24	May 18	May 13	May 10	May 7	May 4	May 2	Apr 29	Apr 23
20°F	May 5	May 2	Apr 30	Apr 27	Apr 23	Apr 19	Apr 16	Apr 12	Apr 6
16°F	Apr 21	Apr 16	Apr 12	Apr 9	Apr 6	Apr 4	Apr 1	Mar 29	Mar 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.

Threshold	10%	20%	30%	40%	50%	60%	70%	80%	90%
36°F	–	–	–	–	–	–	–	–	–
32°F	–	–	–	–	–	–	–	–	–
28°F	Aug 28	Sep 2	Sep 6	Sep 9	Sep 12	Sep 15	Sep 19	Sep 22	Sep 28
24°F	Sep 10	Sep 16	Sep 19	Sep 23	Sep 27	Sep 30	Oct 2	Oct 6	Oct 13
20°F	Sep 23	Sep 29	Oct 2	Oct 6	Oct 10	Oct 14	Oct 19	Oct 23	Oct 29
16°F	Oct 5	Oct 13	Oct 18	Oct 22	Oct 25	Oct 29	Nov 1	Nov 5	Nov 13

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	57	51	46	41	38	34	29	25
32°F	93	85	79	75	69	64	59	52	43
28°F	134	123	116	111	105	99	93	86	75
24°F	161	154	148	144	140	136	131	125	116
20°F	194	184	179	174	169	164	160	155	147
16°F	224	214	209	204	199	195	189	183	174

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: 8,396
Cooling degree days, base 65°F: 180
Growing degree days, base 40°F: 3,225
Growing degree days, base 45°F: 2,306
Growing degree days, base 50°F: 1,548
Growing degree days, base 55°F: 939
Growing degree days, base 60°F: 484

Growing degree days by month, base 50°F

Heating and cooling by month

Month	Heating DD	Cooling DD	Growing DD 50
January	1,358	0	0
February	1,163	0	0
March	1,034	0	0
April	718	0	16
May	463	1	101
June	228	17	255
July	57	89	498
August	72	66	460
September	306	8	188
October	665	0	28
November	989	0	2
December	1,344	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 13.4 km from Caribou 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 USC00108535 (Soda Springs AP). Public domain.