Jackpot Frost Dates and Growing Season

NOAA 1991-2020 normals for Jackpot, 1.4 km from Jackpot, elevation 5233 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Jackpot. 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 29, 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 15	Jun 9	Jun 4	Jun 1	May 29	May 25	May 22	May 18	May 13
24°F	May 30	May 24	May 19	May 16	May 13	May 10	May 6	May 2	Apr 28
20°F	May 16	May 10	May 6	May 2	Apr 29	Apr 26	Apr 22	Apr 18	Apr 10
16°F	May 3	Apr 27	Apr 22	Apr 19	Apr 15	Apr 10	Apr 5	Mar 31	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	–	–	–	–	–	–	–	–	–
28°F	Sep 2	Sep 7	Sep 10	Sep 13	Sep 17	Sep 19	Sep 23	Sep 26	Oct 1
24°F	Sep 14	Sep 18	Sep 22	Sep 26	Sep 29	Oct 1	Oct 4	Oct 8	Oct 12
20°F	Sep 25	Sep 30	Oct 3	Oct 6	Oct 10	Oct 13	Oct 17	Oct 20	Oct 26
16°F	Oct 5	Oct 11	Oct 15	Oct 19	Oct 22	Oct 25	Oct 29	Nov 2	Nov 8

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	82	74	68	62	58	53	47	41	33
32°F	105	98	92	88	83	78	74	67	57
28°F	134	127	121	116	111	106	101	95	86
24°F	158	151	146	142	138	134	129	123	116
20°F	185	178	172	166	162	157	153	148	139
16°F	218	208	202	195	190	185	181	174	164

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: 7,702
Cooling degree days, base 65°F: 290
Growing degree days, base 40°F: 3,505
Growing degree days, base 45°F: 2,550
Growing degree days, base 50°F: 1,772
Growing degree days, base 55°F: 1,136
Growing degree days, base 60°F: 640

Growing degree days by month, base 50°F

Heating and cooling by month

Month	Heating DD	Cooling DD	Growing DD 50
January	1,229	0	0
February	1,018	0	0
March	907	0	1
April	705	0	17
May	459	2	109
June	205	30	292
July	37	143	570
August	57	101	511
September	265	15	230
October	639	0	40
November	951	0	1
December	1,231	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 1.4 km from Jackpot. 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 USC00264016 (Jackpot). Public domain.