Orange County climate

Orange County Frost Dates and Growing Season

NOAA 1991-2020 normals for Orange 9 N, 18.9 km from Orange County, elevation 18 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Orange 9 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 28 and the first fall freeze around November 23, a growing season of about 273 days.

Median at 36°F
last March 16, first November 12
Median at 32°F
last February 28, first November 23
Median at 28°F
last February 3, first December 12

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 13Apr 4Mar 31Mar 22Mar 16Mar 9Mar 4Feb 27Feb 19
32°FMar 29Mar 17Mar 9Mar 4Feb 28Feb 22Feb 15Feb 7Jan 29
28°FMar 9Feb 28Feb 19Feb 11Feb 3Jan 31Jan 25Jan 15Dec 31
24°FFeb 20Feb 6Feb 1Jan 28Jan 23Jan 15Jan 7Dec 31Dec 20
20°FFeb 3Jan 31Jan 26Jan 21Jan 14Jan 10Jan 6Dec 31Dec 22
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 29Nov 1Nov 5Nov 8Nov 12Nov 15Nov 19Nov 25Dec 2
32°FNov 4Nov 8Nov 14Nov 19Nov 23Nov 29Dec 3Dec 9Dec 24
28°FNov 16Nov 23Nov 30Dec 4Dec 12Dec 21Dec 31Jan 6Jan 16
24°FDec 1Dec 12Dec 20Dec 28Jan 2Jan 8Jan 15Jan 25Feb 2
20°FDec 15Dec 25Jan 1Jan 5Jan 9Jan 15Jan 20Jan 29Feb 1
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°F271262256248242236229221214
32°F308297289280273266260249239
28°F352338331321313305297287273
24°F365365365362351342335329309
20°F365365365365365365365357340
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
94% of years
24°F or colder
63% of years
20°F or colder
24% of years
16°F or colder
5% 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
1,752
Cooling degree days, base 65°F
2,429
Growing degree days, base 40°F
9,836
Growing degree days, base 45°F
8,093
Growing degree days, base 50°F
6,448
Growing degree days, base 55°F
4,943
Growing degree days, base 60°F
3,597

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January4567123
February32112165
March18742335
April73102480
May8270727
June0427877
July0504969
August0504969
September2361810
October56153564
November23634277
December41214153

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 18.9 km from Orange County. 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 USC00416680 (Orange 9 N). Public domain.