Dolan Springs Frost Dates and Growing Season

NOAA 1991-2020 normals for Willow Beach, 46.6 km from Dolan Springs, elevation 740 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Willow Beach. 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 7 and the first fall freeze around December 29, a growing season of about 358 days.

Median at 36°F: last January 29, first December 15
Median at 32°F: last January 7, first December 29
Median at 28°F: last January 2, first January 1

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	Feb 20	Feb 12	Feb 5	Feb 2	Jan 29	Jan 23	Jan 18	Jan 12	Jan 4
32°F	Feb 1	Jan 22	Jan 15	Jan 11	Jan 7	Jan 3	Dec 31	Dec 27	Dec 20
28°F	Jan 14	Jan 11	Jan 7	Jan 4	Jan 2	Jan 1	Dec 30	Dec 23	Dec 17
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 29	Dec 5	Dec 8	Dec 11	Dec 15	Dec 19	Dec 22	Dec 26	Jan 1
32°F	Dec 10	Dec 16	Dec 22	Dec 26	Dec 29	Dec 31	Jan 4	Jan 10	Jan 18
28°F	Dec 16	Dec 21	Dec 27	Dec 30	Jan 1	Jan 2	Jan 5	Jan 8	Jan 13
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	347	339	333	326	320	314	308	302	292
32°F	365	365	365	362	358	353	348	340	332
28°F	365	365	365	365	365	365	365	365	361
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: 98% of years
32°F or colder: 63% of years
28°F or colder: 14% of years
24°F or colder: 1% of years
20°F or colder: 0% 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: 1,177
Cooling degree days, base 65°F: 4,644
Growing degree days, base 40°F: 12,593
Growing degree days, base 45°F: 10,773
Growing degree days, base 50°F: 8,991
Growing degree days, base 55°F: 7,347
Growing degree days, base 60°F: 5,901

Growing degree days by month, base 50°F

Heating and cooling by month

Month	Heating DD	Cooling DD	Growing DD 50
January	358	0	125
February	208	6	222
March	87	81	459
April	18	235	668
May	2	519	983
June	0	797	1,247
July	0	989	1,454
August	0	952	1,417
September	0	687	1,137
October	6	332	791
November	125	47	374
December	374	0	116

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 46.6 km from Dolan Springs. 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 USC00029376 (Willow Beach). Public domain.