Gila County Frost Dates and Growing Season

NOAA 1991-2020 normals for Roosevelt 1 S, 32.2 km from Gila County, elevation 2605 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Roosevelt 1 S. 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 January 17 and the first fall freeze around December 25, a growing season of about 342 days.

Median at 36°F: last February 16, first December 8
Median at 32°F: last January 17, first December 25
Median at 28°F: last January 14, first January 10

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	Mar 9	Mar 3	Feb 27	Feb 20	Feb 16	Feb 9	Feb 3	Jan 28	Jan 18
32°F	Feb 18	Feb 9	Feb 2	Jan 25	Jan 17	Jan 10	Jan 4	Dec 31	Dec 21
28°F	Feb 12	Feb 4	Jan 29	Jan 23	Jan 14	Jan 6	Jan 2	Dec 30	Dec 21
24°F	–	–	–	–	–	–	–	–	–
20°F	–	–	–	–	–	–	–	–	–
16°F	–	–	–	–	–	–	–	–	–

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	Nov 24	Nov 28	Dec 3	Dec 6	Dec 8	Dec 11	Dec 14	Dec 19	Dec 25
32°F	Dec 5	Dec 10	Dec 15	Dec 20	Dec 25	Dec 29	Jan 3	Jan 12	Jan 27
28°F	Dec 19	Dec 26	Dec 31	Jan 3	Jan 10	Jan 17	Jan 24	Jan 31	Feb 6
24°F	–	–	–	–	–	–	–	–	–
20°F	–	–	–	–	–	–	–	–	–
16°F	–	–	–	–	–	–	–	–	–

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	329	318	310	303	296	289	283	276	267
32°F	365	363	355	349	342	336	328	319	308
28°F	365	365	365	365	365	365	365	357	339
24°F	365	365	365	365	365	365	365	365	365
20°F	365	365	365	365	365	365	365	365	365
16°F	365	365	365	365	365	365	365	365	365

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: 82% of years
28°F or colder: 25% of years
24°F or colder: 4% of years
20°F or colder: 1% of years
16°F or colder: 0% 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: 1,627
Cooling degree days, base 65°F: 3,559
Growing degree days, base 40°F: 11,059
Growing degree days, base 45°F: 9,254
Growing degree days, base 50°F: 7,545
Growing degree days, base 55°F: 6,024
Growing degree days, base 60°F: 4,709

Growing degree days by month, base 50°F

Heating and cooling by month

Month	Heating DD	Cooling DD	Growing DD 50
January	456	0	58
February	304	0	135
March	160	23	334
April	37	131	543
May	4	379	840
June	0	666	1,116
July	0	801	1,266
August	0	750	1,215
September	0	554	1,004
October	17	233	681
November	187	22	292
December	462	0	61

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 32.2 km from Gila 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 USC00027281 (Roosevelt 1 S). Public domain.