Victor Frost Dates and Growing Season

NOAA 1991-2020 normals for Driggs, 14.2 km from Victor, elevation 6120 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Driggs. 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 June 13 and the first fall freeze around September 9, a growing season of about 86 days.

Median at 32°F: last June 13, first September 9
Median at 28°F: last May 22, first September 20

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	Jun 28	Jun 23	Jun 20	Jun 16	Jun 13	Jun 9	Jun 5	Jun 2	May 27
28°F	Jun 11	Jun 5	Jun 1	May 28	May 22	May 18	May 14	May 10	May 5
24°F	May 24	May 16	May 11	May 8	May 5	May 2	Apr 30	Apr 27	Apr 21
20°F	May 10	May 3	Apr 30	Apr 27	Apr 23	Apr 19	Apr 15	Apr 12	Apr 7
16°F	Apr 27	Apr 21	Apr 15	Apr 11	Apr 8	Apr 5	Apr 2	Mar 30	Mar 24

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	Aug 26	Aug 30	Sep 2	Sep 5	Sep 9	Sep 11	Sep 14	Sep 18	Sep 23
28°F	Sep 4	Sep 9	Sep 13	Sep 17	Sep 20	Sep 23	Sep 27	Sep 30	Oct 4
24°F	Sep 14	Sep 21	Sep 26	Sep 29	Oct 2	Oct 5	Oct 8	Oct 12	Oct 16
20°F	Sep 28	Oct 2	Oct 6	Oct 10	Oct 13	Oct 17	Oct 21	Oct 25	Oct 31
16°F	Oct 7	Oct 14	Oct 20	Oct 23	Oct 26	Oct 29	Nov 1	Nov 4	Nov 9

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	78	72	67	63	59	55	50	44	35
32°F	108	100	95	90	86	82	78	72	64
28°F	142	135	128	124	118	113	109	102	96
24°F	167	161	156	151	147	143	139	133	126
20°F	195	187	182	177	172	168	162	156	148
16°F	222	213	208	203	197	192	188	182	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: 8,414
Cooling degree days, base 65°F: 120
Growing degree days, base 40°F: 3,134
Growing degree days, base 45°F: 2,217
Growing degree days, base 50°F: 1,458
Growing degree days, base 55°F: 850
Growing degree days, base 60°F: 396

Growing degree days by month, base 50°F

Heating and cooling by month

Month	Heating DD	Cooling DD	Growing DD 50
January	1,362	0	0
February	1,144	0	0
March	1,014	0	0
April	729	0	12
May	469	1	90
June	242	8	233
July	58	64	471
August	83	43	426
September	291	4	195
October	670	0	30
November	1,010	0	1
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 14.2 km from Victor. 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 USC00102676 (Driggs). Public domain.