Orange County climate

Orange County Frost Dates and Growing Season

NOAA 1991-2020 normals for Montgomery Orange AP, 12.4 km from Orange County, elevation 365 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Montgomery Orange AP. 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 May 1 and the first fall freeze around October 11, a growing season of about 163 days.

Median at 36°F
last May 13, first October 1
Median at 32°F
last May 1, first October 11
Median at 28°F
last April 19, first October 24

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 27May 23May 19May 16May 13May 10May 6May 2Apr 28
32°FMay 17May 12May 9May 5May 1Apr 29Apr 26Apr 22Apr 18
28°FMay 4Apr 29Apr 25Apr 22Apr 19Apr 16Apr 13Apr 9Apr 4
24°FApr 20Apr 16Apr 11Apr 9Apr 6Apr 3Mar 31Mar 29Mar 23
20°FApr 8Apr 3Mar 31Mar 29Mar 26Mar 22Mar 19Mar 15Mar 9
16°FMar 30Mar 24Mar 20Mar 17Mar 14Mar 11Mar 7Mar 3Feb 26

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°FSep 19Sep 24Sep 27Sep 30Oct 1Oct 4Oct 6Oct 10Oct 14
32°FSep 30Oct 2Oct 5Oct 8Oct 11Oct 14Oct 18Oct 22Oct 27
28°FOct 9Oct 14Oct 18Oct 21Oct 24Oct 28Oct 31Nov 3Nov 8
24°FOct 21Oct 26Oct 31Nov 2Nov 4Nov 7Nov 11Nov 14Nov 20
20°FNov 2Nov 6Nov 11Nov 14Nov 18Nov 21Nov 25Nov 30Dec 4
16°FNov 14Nov 20Nov 24Nov 28Dec 1Dec 3Dec 7Dec 14Dec 20

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°F162155150147142138133129123
32°F183176171166163158154149142
28°F209202197193188183179173165
24°F234227222218214210205200193
20°F261253248243238234230225218
16°F283277272267263259254248240

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
100% of years
16°F or colder
100% 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
6,266
Cooling degree days, base 65°F
617
Growing degree days, base 40°F
4,847
Growing degree days, base 45°F
3,712
Growing degree days, base 50°F
2,726
Growing degree days, base 55°F
1,875
Growing degree days, base 60°F
1,167

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,21000
February1,03301
March877012
April516475
May22828278
June45117522
July5228688
August14179631
September12755381
October4315119
November735016
December1,04502

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 12.4 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 USW00004789 (Montgomery Orange AP). Public domain.