Sun Lakes climate

Sun Lakes Frost Dates and Growing Season

NOAA 1991-2020 normals for Maricopa 4 N, 18 km from Sun Lakes, elevation 1160 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Maricopa 4 N. 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 23 and the first fall freeze around November 24, a growing season of about 274 days.

Median at 36°F
last March 12, first November 14
Median at 32°F
last February 23, first November 24
Median at 28°F
last February 2, first December 6

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 10Mar 31Mar 23Mar 17Mar 12Mar 9Mar 5Mar 1Feb 24
32°FMar 15Mar 8Mar 3Feb 28Feb 23Feb 18Feb 12Feb 4Jan 29
28°FFeb 28Feb 19Feb 12Feb 6Feb 2Jan 29Jan 22Jan 12Dec 31
24°FFeb 8Jan 31Jan 24Jan 16Jan 8Jan 3Dec 30Dec 23Dec 16
20°FJan 28Jan 20Jan 11Jan 6Jan 3Dec 31Dec 25Dec 18Dec 11
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°FOct 27Nov 3Nov 7Nov 11Nov 14Nov 16Nov 19Nov 22Nov 28
32°FNov 10Nov 15Nov 18Nov 21Nov 24Nov 27Dec 1Dec 4Dec 8
28°FNov 21Nov 26Nov 30Dec 2Dec 6Dec 9Dec 12Dec 17Dec 23
24°FDec 1Dec 5Dec 10Dec 14Dec 18Dec 23Dec 29Jan 3Jan 14
20°FDec 6Dec 12Dec 18Dec 24Dec 30Jan 2Jan 6Jan 12Jan 23
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°F267259253248243238232224215
32°F304293285280274269263255245
28°F344334325318310304297287278
24°F365365358351345339334326314
20°F365365365365365365364354342
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
100% of years
28°F or colder
99% of years
24°F or colder
85% of years
20°F or colder
35% of years
16°F or colder
4% 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
1,382
Cooling degree days, base 65°F
3,946
Growing degree days, base 40°F
11,692
Growing degree days, base 45°F
9,882
Growing degree days, base 50°F
8,135
Growing degree days, base 55°F
6,536
Growing degree days, base 60°F
5,142

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January3770121
February2453186
March12341384
April29164585
May2417880
June06861,136
July08791,344
August08451,310
September06211,071
October16261710
November16931318
December421091

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 18 km from Sun Lakes. 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 USC00025270 (Maricopa 4 N). Public domain.