Arivaca Junction climate

Arivaca Junction Frost Dates and Growing Season

NOAA 1991-2020 normals for Tumacacori Nm, 17.7 km from Arivaca Junction, elevation 3267 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Tumacacori Nm. 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 April 5 and the first fall freeze around November 10, a growing season of about 217 days.

Median at 36°F
last April 23, first October 30
Median at 32°F
last April 5, first November 10
Median at 28°F
last March 12, first November 20

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°FMay 9May 4Apr 30Apr 27Apr 23Apr 19Apr 15Apr 11Apr 6
32°FApr 25Apr 19Apr 13Apr 9Apr 5Apr 1Mar 28Mar 22Mar 13
28°FApr 8Mar 30Mar 25Mar 17Mar 12Mar 7Mar 2Feb 26Feb 16
24°FMar 11Mar 4Feb 28Feb 23Feb 16Feb 11Feb 6Jan 28Jan 15
20°FFeb 24Feb 15Feb 8Feb 1Jan 24Jan 16Jan 7Dec 26Dec 13
16°FFeb 11Feb 2Jan 24Jan 16Jan 5Dec 31Dec 24Dec 14Dec 2

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 13Oct 19Oct 23Oct 27Oct 30Nov 1Nov 5Nov 9Nov 14
32°FOct 21Oct 30Nov 3Nov 7Nov 10Nov 14Nov 17Nov 21Nov 27
28°FNov 1Nov 7Nov 12Nov 16Nov 20Nov 23Nov 27Dec 2Dec 9
24°FNov 10Nov 18Nov 23Nov 27Dec 2Dec 6Dec 11Dec 16Dec 26
20°FNov 21Nov 28Dec 3Dec 9Dec 14Dec 19Dec 26Jan 3Jan 18
16°FNov 27Dec 6Dec 13Dec 20Dec 28Jan 1Jan 8Jan 19Feb 5

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°F212205199194190185180173166
32°F247235230223217211206199190
28°F279270262257251243236227217
24°F323311303294286279272262250
20°F365354343335328321311302288
16°F365365365365365361348337325

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
100% of years
24°F or colder
100% of years
20°F or colder
88% of years
16°F or colder
48% 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
2,441
Cooling degree days, base 65°F
1,752
Growing degree days, base 40°F
8,482
Growing degree days, base 45°F
6,767
Growing degree days, base 50°F
5,195
Growing degree days, base 55°F
3,831
Growing degree days, base 60°F
2,692

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January538048
February427069
March3173185
April16323317
May46125545
June1363811
July0468933
August0419884
September3277724
October8570453
November3125182
December550045

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 17.7 km from Arivaca Junction. 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 USC00028865 (Tumacacori Nm). Public domain.