Joshua Tree climate

Joshua Tree Frost Dates and Growing Season

NOAA 1991-2020 normals for Joshua Tree, 3.8 km from Joshua Tree, elevation 2563 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Joshua Tree. 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 February 28 and the first fall freeze around December 1, a growing season of about 273 days.

Median at 36°F
last March 30, first November 16
Median at 32°F
last February 28, first December 1
Median at 28°F
last January 24, first December 15

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°FApr 18Apr 11Apr 7Apr 3Mar 30Mar 24Mar 18Mar 13Mar 1
32°FMar 28Mar 19Mar 11Mar 5Feb 28Feb 22Feb 15Feb 4Jan 21
28°FFeb 28Feb 20Feb 11Feb 3Jan 24Jan 14Jan 6Jan 1Dec 22
24°FFeb 16Feb 6Jan 24Jan 11Jan 5Jan 1Dec 30Dec 21Dec 13
20°FFeb 12Jan 13Jan 6Jan 2Dec 31Dec 29Dec 27Dec 23Dec 18
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°FOct 28Nov 3Nov 8Nov 13Nov 16Nov 20Nov 23Nov 27Dec 2
32°FNov 12Nov 20Nov 24Nov 28Dec 1Dec 5Dec 8Dec 12Dec 17
28°FNov 28Dec 4Dec 8Dec 12Dec 15Dec 19Dec 23Dec 28Jan 7
24°FDec 9Dec 14Dec 19Dec 25Dec 29Jan 1Jan 6Jan 17Feb 6
20°FDec 15Dec 21Dec 24Dec 28Dec 30Jan 1Jan 4Jan 11Feb 9
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°F263253244237231225219212201
32°F315300289280273266259250240
28°F359349341334327318309299285
24°F365365365365365360352343330
20°F365365365365365365365365362
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
100% of years
28°F or colder
95% of years
24°F or colder
49% of years
20°F or colder
12% of years
16°F or colder
1% 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
2,225
Cooling degree days, base 65°F
2,442
Growing degree days, base 40°F
9,368
Growing degree days, base 45°F
7,635
Growing degree days, base 50°F
6,041
Growing degree days, base 55°F
4,634
Growing degree days, base 60°F
3,435

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January493062
February3861105
March2787219
April13449370
May38189615
June4401848
July06391,103
August06151,080
September6400844
October62127531
November28515211
December539052

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 3.8 km from Joshua Tree. Low ground, valleys and open fields freeze earlier and later than a town center or a hillside.

More

Sources

NOAA NCEI U.S. Climate Normals, 1991-2020, annual and seasonal normals for station USC00044405 (Joshua Tree). Public domain.