Carefree climate

Carefree Frost Dates and Growing Season

NOAA 1991-2020 normals for Carefree, 1.6 km from Carefree, elevation 2530 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Carefree. 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 4 and the first fall freeze around December 16, a growing season of about 313 days.

Median at 36°F
last March 5, first December 1
Median at 32°F
last February 4, first December 16
Median at 28°F
last January 14, first January 1

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 2Mar 24Mar 15Mar 10Mar 5Feb 27Feb 20Feb 12Jan 31
32°FMar 9Mar 1Feb 20Feb 13Feb 4Jan 30Jan 20Jan 11Jan 3
28°FFeb 22Feb 10Jan 31Jan 24Jan 14Jan 8Jan 3Dec 29Dec 19
24°FFeb 14Feb 4Jan 25Jan 15Jan 7Jan 4Jan 2Dec 28Dec 19
20°F–––––––––
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 13Nov 19Nov 23Nov 27Dec 1Dec 4Dec 8Dec 12Dec 18
32°FNov 24Dec 1Dec 6Dec 12Dec 16Dec 20Dec 25Jan 1Jan 15
28°FDec 5Dec 15Dec 24Dec 29Jan 1Jan 6Jan 13Jan 26Feb 9
24°FDec 15Dec 27Jan 1Jan 3Jan 6Jan 10Jan 21Feb 1Feb 11
20°F–––––––––
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°F307293283275269262255247236
32°F351341331322313304295285273
28°F365365365363357350340330316
24°F365365365365365365365365350
20°F365365365365365365365365365
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
60% of years
24°F or colder
15% of years
20°F or colder
0% of years
16°F or colder
0% 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
1,427
Cooling degree days, base 65°F
3,512
Growing degree days, base 40°F
11,212
Growing degree days, base 45°F
9,410
Growing degree days, base 50°F
7,680
Growing degree days, base 55°F
6,093
Growing degree days, base 60°F
4,701

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January3701134
February2664180
March16137349
April56122517
May9353809
June06101,060
July07641,229
August07471,212
September05611,011
October20262707
November15750351
December3901121

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 1.6 km from Carefree. 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 USC00021282 (Carefree). Public domain.