Half Moon climate

Half Moon Frost Dates and Growing Season

NOAA 1991-2020 normals for Jacksonville Eoc, 6.2 km from Half Moon, elevation 17 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Jacksonville Eoc. 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 March 31 and the first fall freeze around November 8, a growing season of about 224 days.

Median at 36°F
last April 9, first October 31
Median at 32°F
last March 31, first November 8
Median at 28°F
last March 18, first November 21

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 22Apr 18Apr 15Apr 12Apr 9Apr 6Apr 3Mar 31Mar 25
32°FApr 15Apr 9Apr 6Apr 2Mar 31Mar 28Mar 25Mar 19Mar 13
28°FApr 3Mar 29Mar 25Mar 21Mar 18Mar 14Mar 9Mar 3Feb 25
24°FMar 23Mar 17Mar 12Mar 5Mar 1Feb 26Feb 21Feb 13Feb 3
20°FMar 8Mar 1Feb 23Feb 16Feb 8Feb 2Jan 29Jan 20Jan 10
16°FFeb 21Feb 8Feb 1Jan 30Jan 26Jan 20Jan 15Jan 10Jan 1

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 18Oct 22Oct 25Oct 29Oct 31Nov 2Nov 4Nov 7Nov 11
32°FOct 27Oct 31Nov 3Nov 5Nov 8Nov 11Nov 15Nov 20Nov 25
28°FNov 5Nov 10Nov 13Nov 17Nov 21Nov 25Nov 30Dec 4Dec 13
24°FNov 16Nov 23Nov 28Dec 1Dec 5Dec 11Dec 21Dec 30Jan 8
20°FNov 30Dec 8Dec 16Dec 26Jan 1Jan 5Jan 11Jan 18Feb 1
16°FDec 18Dec 28Jan 1Jan 6Jan 11Jan 14Jan 19Jan 26Feb 2

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°F223216212208204201197194187
32°F248240235230224220216211205
28°F281270262256250244239233224
24°F317305297289282276269261250
20°F353341333326316309303296285
16°F365365365358349342335329313

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
94% of years
16°F or colder
68% 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
2,767
Cooling degree days, base 65°F
1,880
Growing degree days, base 40°F
8,399
Growing degree days, base 45°F
6,785
Growing degree days, base 50°F
5,312
Growing degree days, base 55°F
4,004
Growing degree days, base 60°F
2,859

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January644162
February518271
March39613163
April15858360
May32173606
June1358807
July0482947
August0432897
September6271715
October12375422
November34612171
December544491

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 6.2 km from Half Moon. 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 USC00314471 (Jacksonville Eoc). Public domain.