Miracle Valley climate

Miracle Valley Frost Dates and Growing Season

NOAA 1991-2020 normals for Coronado Nmem, 10.3 km from Miracle Valley, elevation 5242 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Coronado Nmem. 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 7 and the first fall freeze around November 9, a growing season of about 213 days.

Median at 36°F
last April 24, first October 31
Median at 32°F
last April 7, first November 9
Median at 28°F
last March 19, 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 12May 5May 1Apr 28Apr 24Apr 21Apr 16Apr 12Apr 5
32°FApr 27Apr 20Apr 15Apr 11Apr 7Apr 4Mar 31Mar 27Mar 19
28°FApr 12Apr 4Mar 30Mar 24Mar 19Mar 13Mar 7Mar 1Feb 22
24°FMar 25Mar 12Mar 6Feb 28Feb 22Feb 16Feb 10Feb 3Jan 23
20°FFeb 26Feb 17Feb 11Feb 5Jan 31Jan 23Jan 13Jan 4Dec 26
16°FFeb 14Feb 7Feb 1Jan 27Jan 19Jan 10Jan 3Dec 29Dec 21

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 16Oct 21Oct 25Oct 28Oct 31Nov 2Nov 5Nov 9Nov 14
32°FOct 25Oct 30Nov 2Nov 5Nov 9Nov 12Nov 16Nov 20Nov 27
28°FNov 1Nov 8Nov 12Nov 16Nov 20Nov 24Nov 28Dec 3Dec 7
24°FNov 13Nov 20Nov 26Nov 30Dec 4Dec 7Dec 13Dec 19Dec 26
20°FNov 28Dec 7Dec 13Dec 19Dec 23Dec 28Jan 3Jan 13Jan 28
16°FDec 15Dec 22Dec 28Jan 1Jan 7Jan 16Jan 23Jan 31Feb 10

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°F211203198193189185179174166
32°F238230223218213207203197189
28°F275264256249242235230222212
24°F324309300290283276268258245
20°F365353345336329323316304293
16°F365365365365365361348335324

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
90% of years
16°F or colder
45% 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
2,660
Cooling degree days, base 65°F
1,323
Growing degree days, base 40°F
7,846
Growing degree days, base 45°F
6,163
Growing degree days, base 50°F
4,648
Growing degree days, base 55°F
3,339
Growing degree days, base 60°F
2,233

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January594028
February461055
March3492160
April16618310
May49119535
June1330778
July0336801
August0281746
September5188633
October9947417
November3462154
December591032

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 10.3 km from Miracle Valley. 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 USC00022140 (Coronado Nmem). Public domain.