Williamsburg climate

Williamsburg Frost Dates and Growing Season

NOAA 1991-2020 normals for Williamsburg 2 N, 3.4 km from Williamsburg, elevation 70 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Williamsburg 2 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 March 31 and the first fall freeze around November 10, a growing season of about 225 days.

Median at 36°F
last April 12, first November 1
Median at 32°F
last March 31, first November 10
Median at 28°F
last March 20, first November 23

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 1Apr 23Apr 19Apr 15Apr 12Apr 8Apr 5Apr 2Mar 28
32°FApr 14Apr 9Apr 5Apr 2Mar 31Mar 28Mar 26Mar 21Mar 15
28°FApr 4Mar 30Mar 27Mar 23Mar 20Mar 16Mar 12Mar 6Feb 28
24°FMar 23Mar 18Mar 13Mar 9Mar 5Mar 2Feb 26Feb 21Feb 11
20°FMar 13Mar 6Mar 1Feb 24Feb 19Feb 13Feb 7Feb 2Jan 23
16°FMar 2Feb 22Feb 13Feb 6Feb 2Jan 29Jan 23Jan 17Jan 8

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 21Oct 24Oct 27Oct 29Nov 1Nov 2Nov 4Nov 8Nov 12
32°FOct 29Nov 1Nov 5Nov 7Nov 10Nov 13Nov 16Nov 20Nov 26
28°FNov 7Nov 11Nov 15Nov 19Nov 23Nov 28Dec 2Dec 6Dec 13
24°FNov 18Nov 27Dec 1Dec 4Dec 8Dec 14Dec 20Dec 27Jan 2
20°FDec 4Dec 11Dec 18Dec 25Dec 29Jan 2Jan 6Jan 13Jan 22
16°FDec 16Dec 25Dec 31Jan 5Jan 10Jan 14Jan 18Jan 24Feb 1

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°F221215211207203199194189182
32°F248239233230225222217213205
28°F277269262257252246240235227
24°F308299292286280275269264254
20°F337329322314308304299291280
16°F365356347341334330321312303

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
98% of years
16°F or colder
84% 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
3,491
Cooling degree days, base 65°F
1,585
Growing degree days, base 40°F
7,514
Growing degree days, base 45°F
6,007
Growing degree days, base 50°F
4,664
Growing degree days, base 55°F
3,476
Growing degree days, base 60°F
2,449

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January780026
February640132
March4987108
April22642286
May65130530
June6301745
July0445910
August0391856
September14218654
October16546353
November4255121
December672143

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 3.4 km from Williamsburg. 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 USC00449151 (Williamsburg 2 N). Public domain.