Cactus climate

Cactus Frost Dates and Growing Season

NOAA 1991-2020 normals for Encinal, 7.9 km from Cactus, elevation 545 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Encinal. 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 21 and the first fall freeze around December 9, a growing season of about 296 days.

Median at 36°F
last March 6, first November 26
Median at 32°F
last February 21, first December 9
Median at 28°F
last January 31, first December 27

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 30Mar 21Mar 15Mar 10Mar 6Mar 2Feb 26Feb 19Feb 6
32°FMar 16Mar 8Mar 2Feb 27Feb 21Feb 14Feb 5Jan 29Jan 16
28°FMar 5Feb 26Feb 15Feb 6Jan 31Jan 26Jan 16Jan 6Dec 24
24°FFeb 21Feb 7Jan 29Jan 22Jan 14Jan 7Dec 31Dec 25Dec 15
20°FFeb 1Jan 22Jan 16Jan 11Jan 5Jan 3Dec 31Dec 26Dec 17
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 7Nov 14Nov 19Nov 23Nov 26Dec 1Dec 4Dec 8Dec 14
32°FNov 21Nov 28Dec 2Dec 5Dec 9Dec 13Dec 19Dec 29Jan 8
28°FDec 5Dec 10Dec 15Dec 21Dec 27Jan 2Jan 8Jan 19Feb 3
24°FDec 12Dec 17Dec 23Dec 29Jan 2Jan 6Jan 13Jan 24Feb 8
20°FDec 17Dec 25Dec 30Jan 1Jan 4Jan 8Jan 15Jan 21Feb 1
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°F297285277270264258252244235
32°F337324313304296288282275263
28°F365361351342334326318306294
24°F365365365365365360351341326
20°F365365365365365365365365358
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
98% of years
28°F or colder
84% of years
24°F or colder
46% of years
20°F or colder
13% 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
1,115
Cooling degree days, base 65°F
3,606
Growing degree days, base 40°F
11,629
Growing degree days, base 45°F
9,835
Growing degree days, base 50°F
8,097
Growing degree days, base 55°F
6,457
Growing degree days, base 60°F
4,951

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January31917211
February19836281
March106112480
April21247677
May2447910
June05941,044
July06421,107
August06591,124
September0482932
October19269715
November13388415
December31715204

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 7.9 km from Cactus. 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 USC00412906 (Encinal). Public domain.