Darien climate

Darien Frost Dates and Growing Season

NOAA 1991-2020 normals for Sapelo Is, 14.9 km from Darien, elevation 10 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Sapelo Is. 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 20 and the first fall freeze around December 19, a growing season of about 298 days.

Median at 36°F
last March 6, first November 29
Median at 32°F
last February 20, first December 19
Median at 28°F
last February 3, first January 3

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 27Mar 21Mar 16Mar 11Mar 6Mar 2Feb 26Feb 21Feb 12
32°FMar 16Mar 6Mar 2Feb 25Feb 20Feb 15Feb 8Feb 2Jan 25
28°FMar 3Feb 23Feb 15Feb 9Feb 3Jan 30Jan 23Jan 15Jan 2
24°FFeb 18Feb 11Feb 2Jan 30Jan 23Jan 17Jan 12Jan 2Dec 25
20°FFeb 14Feb 7Feb 3Jan 30Jan 23Jan 15Jan 8Dec 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°FNov 7Nov 15Nov 19Nov 24Nov 29Dec 2Dec 7Dec 13Dec 25
32°FNov 23Nov 30Dec 5Dec 11Dec 19Dec 24Jan 1Jan 7Jan 15
28°FDec 6Dec 16Dec 23Dec 30Jan 3Jan 8Jan 14Jan 23Feb 4
24°FDec 18Dec 26Jan 1Jan 7Jan 13Jan 18Jan 27Feb 1Feb 11
20°FDec 19Dec 25Jan 1Jan 12Jan 18Jan 24Jan 31Feb 5Feb 11
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°F298287279274268262256248239
32°F332318311305298292285276266
28°F365355344335329321314306294
24°F365365365365363354343333317
20°F365365365365365365365365343
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
99% of years
28°F or colder
85% of years
24°F or colder
50% of years
20°F or colder
16% of years
16°F or colder
2% 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
1,424
Cooling degree days, base 65°F
2,690
Growing degree days, base 40°F
10,410
Growing degree days, base 45°F
8,633
Growing degree days, base 50°F
6,930
Growing degree days, base 55°F
5,347
Growing degree days, base 60°F
3,923

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January3996151
February2937174
March17436340
April51116515
May5307767
June0461911
July05601,025
August0532997
September0408858
October27196634
November15549353
December31913207

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 14.9 km from Darien. 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 USC00097808 (Sapelo Is). Public domain.