Twentynine Palms climate

Twentynine Palms Frost Dates and Growing Season

NOAA 1991-2020 normals for Twentynine Palms, 1.8 km from Twentynine Palms, elevation 1975 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Twentynine Palms. 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 24 and the first fall freeze around December 10, a growing season of about 321 days.

Median at 36°F
last February 19, first November 27
Median at 32°F
last January 24, first December 10
Median at 28°F
last January 3, first December 23

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.

Threshold10%20%30%40%50%60%70%80%90%
36°FMar 11Mar 5Feb 28Feb 23Feb 19Feb 14Feb 8Feb 2Jan 22
32°FFeb 22Feb 13Feb 6Jan 31Jan 24Jan 14Jan 6Jan 1Dec 22
28°FFeb 8Jan 31Jan 19Jan 8Jan 3Dec 31Dec 25Dec 18Dec 11
24°FFeb 6Jan 27Jan 17Jan 8Jan 4Jan 1Dec 30Dec 25Dec 14
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.

Threshold10%20%30%40%50%60%70%80%90%
36°FNov 13Nov 18Nov 22Nov 25Nov 27Nov 30Dec 3Dec 7Dec 13
32°FNov 24Nov 29Dec 3Dec 7Dec 10Dec 14Dec 18Dec 24Jan 1
28°FDec 3Dec 9Dec 13Dec 18Dec 23Dec 28Jan 1Jan 8Jan 28
24°FDec 12Dec 20Dec 26Dec 30Jan 2Jan 5Jan 11Jan 18Jan 31
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.

Threshold10%20%30%40%50%60%70%80%90%
36°F313300292286280275270263254
32°F354344335328321314307296284
28°F365365365363357349343334324
24°F365365365365365365365365355
20°F365365365365365365365365365
16°F365365365365365365365365365

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
97% of years
28°F or colder
63% of years
24°F or colder
17% 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
1,511
Cooling degree days, base 65°F
3,482
Growing degree days, base 40°F
11,098
Growing degree days, base 45°F
9,297
Growing degree days, base 50°F
7,576
Growing degree days, base 55°F
6,013
Growing degree days, base 60°F
4,655

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January3871118
February2675177
March14341365
April48132534
May7360818
June06021,052
July07971,262
August07611,226
September0537987
October26219659
November19827290
December436088

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 1.8 km from Twentynine Palms. Low ground, valleys and open fields freeze earlier and later than a town center or a hillside.

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Sources

NOAA NCEI U.S. Climate Normals, 1991-2020, annual and seasonal normals for station USC00049099 (Twentynine Palms). Public domain.