New Hanover County climate

New Hanover County Frost Dates and Growing Season

NOAA 1991-2020 normals for Wilmington 7 Se, 4.4 km from New Hanover County, elevation 30 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Wilmington 7 Se. 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 20 and the first fall freeze around November 15, a growing season of about 241 days.

Median at 36°F
last April 2, first November 5
Median at 32°F
last March 20, first November 15
Median at 28°F
last March 3, first November 28

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 17Apr 13Apr 9Apr 6Apr 2Mar 31Mar 27Mar 23Mar 17
32°FApr 8Apr 2Mar 29Mar 24Mar 20Mar 16Mar 12Mar 7Feb 28
28°FMar 25Mar 18Mar 13Mar 7Mar 3Feb 28Feb 24Feb 19Feb 8
24°FMar 11Mar 4Feb 28Feb 22Feb 17Feb 11Feb 3Jan 30Jan 18
20°FFeb 27Feb 16Feb 7Feb 1Jan 30Jan 23Jan 16Jan 11Jan 1
16°FFeb 12Feb 2Jan 31Jan 25Jan 21Jan 16Jan 11Jan 5Dec 28

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

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°F240232227222218214210205200
32°F267258252247241237231224218
28°F304292283275270265258251243
24°F340330321312305298292283271
20°F365364355346338332323314303
16°F365365365365365365353342330

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
99% of years
20°F or colder
82% of years
16°F or colder
45% 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
2,431
Cooling degree days, base 65°F
2,131
Growing degree days, base 40°F
8,940
Growing degree days, base 45°F
7,284
Growing degree days, base 50°F
5,755
Growing degree days, base 55°F
4,381
Growing degree days, base 60°F
3,174

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January588483
February464496
March33817200
April12960387
May20211656
June1394843
July0522987
August0473938
September2323771
October83103487
November30916198
December4985110

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 4.4 km from New Hanover County. 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 USC00319461 (Wilmington 7 Se). Public domain.