Barstow climate

Barstow Frost Dates and Growing Season

NOAA 1991-2020 normals for Barstow, 0.7 km from Barstow, elevation 2220 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Barstow. 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 22 and the first fall freeze around November 23, a growing season of about 271 days.

Median at 36°F
last March 17, first November 12
Median at 32°F
last February 22, first November 23
Median at 28°F
last January 30, first December 6

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 14Apr 6Mar 30Mar 23Mar 17Mar 11Mar 6Feb 28Feb 24
32°FMar 24Mar 10Mar 3Feb 27Feb 22Feb 16Feb 10Feb 4Jan 29
28°FFeb 25Feb 16Feb 8Feb 3Jan 30Jan 24Jan 18Jan 11Jan 2
24°FFeb 7Jan 30Jan 22Jan 15Jan 10Jan 4Dec 31Dec 25Dec 13
20°FJan 24Jan 17Jan 10Jan 5Jan 1Dec 28Dec 22Dec 13Dec 5
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 31Nov 4Nov 7Nov 9Nov 12Nov 15Nov 18Nov 21Nov 26
32°FNov 9Nov 14Nov 17Nov 20Nov 23Nov 26Dec 1Dec 4Dec 8
28°FNov 18Nov 24Nov 29Dec 2Dec 6Dec 10Dec 14Dec 20Dec 28
24°FNov 29Dec 5Dec 10Dec 17Dec 22Dec 26Dec 31Jan 6Jan 19
20°FNov 30Dec 7Dec 14Dec 21Dec 26Dec 30Jan 4Jan 10Jan 17
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°F266256249243237230224217208
32°F304292284277271264258250239
28°F341332324316310304296288276
24°F365365358352346338332324312
20°F365365365365365365365358347
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
99% of years
24°F or colder
81% of years
20°F or colder
33% of years
16°F or colder
4% 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
2,324
Cooling degree days, base 65°F
2,615
Growing degree days, base 40°F
9,440
Growing degree days, base 45°F
7,710
Growing degree days, base 50°F
6,141
Growing degree days, base 55°F
4,780
Growing degree days, base 60°F
3,609

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January553029
February390188
March26011232
April11862397
May31227660
June2467915
July06801,145
August06421,107
September3402849
October63118520
November3195172
December584026

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 0.7 km from Barstow. 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 USC00040521 (Barstow). Public domain.