Cactus Forest climate

Cactus Forest Frost Dates and Growing Season

NOAA 1991-2020 normals for Florence, 10.6 km from Cactus Forest, elevation 1400 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Florence. 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 January 30 and the first fall freeze around December 12, a growing season of about 319 days.

Median at 36°F
last February 21, first November 29
Median at 32°F
last January 30, first December 12
Median at 28°F
last January 8, first December 26

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°FMar 13Mar 6Mar 1Feb 26Feb 21Feb 17Feb 11Feb 3Jan 25
32°FFeb 24Feb 17Feb 10Feb 4Jan 30Jan 20Jan 10Jan 4Dec 27
28°FFeb 11Feb 2Jan 22Jan 14Jan 8Jan 2Dec 29Dec 19Dec 11
24°FJan 29Jan 20Jan 15Jan 10Jan 6Jan 3Dec 31Dec 26Dec 14
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 12Nov 18Nov 23Nov 26Nov 29Dec 2Dec 6Dec 11Dec 19
32°FNov 22Nov 29Dec 4Dec 7Dec 12Dec 16Dec 23Jan 1Jan 12
28°FDec 1Dec 8Dec 13Dec 19Dec 26Dec 31Jan 6Jan 16Jan 31
24°FDec 11Dec 23Dec 28Dec 31Jan 3Jan 7Jan 11Jan 18Jan 27
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°F312301293287281275268261250
32°F354341333326319312305296286
28°F365365365365362353343336324
24°F365365365365365365365365362
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
95% of years
28°F or colder
57% of years
24°F or colder
16% of years
20°F or colder
2% 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
1,157
Cooling degree days, base 65°F
3,877
Growing degree days, base 40°F
11,846
Growing degree days, base 45°F
10,028
Growing degree days, base 50°F
8,251
Growing degree days, base 55°F
6,596
Growing degree days, base 60°F
5,135

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January3153172
February2195212
March10366428
April31169588
May3391853
June06511,101
July08241,289
August07891,254
September06131,063
October15303753
November12960386
December3412152

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 10.6 km from Cactus Forest. 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 USC00023027 (Florence). Public domain.