Patagonia climate

Patagonia Frost Dates and Growing Season

NOAA 1991-2020 normals for Nogales Intl AP, 15.8 km from Patagonia, elevation 3932 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Nogales Intl AP. 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 March 20 and the first fall freeze around November 17, a growing season of about 239 days.

Median at 36°F
last April 13, first November 5
Median at 32°F
last March 20, first November 17
Median at 28°F
last February 23, first November 30

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 29Apr 24Apr 19Apr 16Apr 13Apr 9Apr 6Apr 1Mar 24
32°FApr 13Apr 6Mar 31Mar 26Mar 20Mar 14Mar 9Mar 3Feb 24
28°FMar 21Mar 11Mar 5Feb 28Feb 23Feb 17Feb 10Feb 4Jan 25
24°FFeb 23Feb 15Feb 9Feb 5Jan 31Jan 24Jan 16Jan 9Dec 28
20°FFeb 10Feb 3Jan 27Jan 20Jan 13Jan 7Jan 2Dec 27Dec 19
16°FFeb 6Jan 30Jan 24Jan 19Jan 10Jan 7Jan 4Dec 30Dec 24

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 20Oct 26Oct 29Nov 1Nov 5Nov 8Nov 11Nov 15Nov 20
32°FOct 30Nov 4Nov 9Nov 13Nov 17Nov 20Nov 24Nov 29Dec 3
28°FNov 11Nov 17Nov 22Nov 25Nov 30Dec 3Dec 6Dec 11Dec 17
24°FNov 24Dec 1Dec 8Dec 13Dec 17Dec 22Dec 27Jan 3Jan 18
20°FDec 11Dec 18Dec 26Dec 30Jan 3Jan 9Jan 17Jan 26Feb 4
16°FDec 24Dec 30Jan 3Jan 5Jan 9Jan 17Jan 23Jan 30Feb 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°F229221216210205201197191183
32°F272261253246239233227219208
28°F310298292286279272265258245
24°F357344336329322315307299287
20°F365365365365365357348339328
16°F365365365365365365365365363

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
96% of years
20°F or colder
52% of years
16°F or colder
12% 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
2,039
Cooling degree days, base 65°F
1,977
Growing degree days, base 40°F
9,080
Growing degree days, base 45°F
7,317
Growing degree days, base 50°F
5,666
Growing degree days, base 55°F
4,208
Growing degree days, base 60°F
2,981

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January467074
February3721101
March2605230
April12027359
May25177617
June0439889
July0481946
August0431896
September1313762
October5595507
November2578221
December484066

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 15.8 km from Patagonia. 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 USW00003196 (Nogales Intl AP). Public domain.