Williamsburg climate

Williamsburg Frost Dates and Growing Season

NOAA 1991-2020 normals for Worthington, 15.7 km from Williamsburg, elevation 1285 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Worthington. 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 13 and the first fall freeze around October 2, a growing season of about 144 days.

Median at 36°F
last May 25, first September 22
Median at 32°F
last May 13, first October 2
Median at 28°F
last April 30, first October 14

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°FJun 7Jun 3May 31May 28May 25May 22May 20May 16May 11
32°FMay 26May 21May 18May 15May 13May 10May 6May 3Apr 29
28°FMay 13May 8May 4May 2Apr 30Apr 27Apr 24Apr 20Apr 15
24°FApr 30Apr 24Apr 21Apr 17Apr 15Apr 11Apr 8Apr 5Apr 2
20°FApr 16Apr 11Apr 7Apr 5Apr 3Apr 2Mar 31Mar 27Mar 20
16°FApr 6Apr 3Apr 1Mar 30Mar 28Mar 24Mar 20Mar 17Mar 13

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 10Sep 14Sep 17Sep 19Sep 22Sep 24Sep 27Sep 30Oct 3
32°FSep 20Sep 24Sep 28Sep 30Oct 2Oct 4Oct 6Oct 10Oct 15
28°FOct 1Oct 3Oct 7Oct 10Oct 14Oct 18Oct 21Oct 25Oct 31
24°FOct 10Oct 16Oct 21Oct 25Oct 29Nov 1Nov 3Nov 7Nov 12
20°FOct 25Nov 1Nov 2Nov 5Nov 8Nov 11Nov 14Nov 18Nov 22
16°FNov 5Nov 11Nov 15Nov 18Nov 20Nov 23Nov 27Dec 1Dec 5

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°F139132127123120117112108102
32°F162156151147144140136131123
28°F190183177172168164160155147
24°F216209205200196192186181172
20°F238231226222217214210206197
16°F260252247243238234230225218

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
7,439
Cooling degree days, base 65°F
301
Growing degree days, base 40°F
3,946
Growing degree days, base 45°F
2,924
Growing degree days, base 50°F
2,046
Growing degree days, base 55°F
1,308
Growing degree days, base 60°F
716

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,34201
February1,15800
March1,03704
April647238
May33512183
June11255395
July27119556
August4787505
September20026286
October539167
November83709
December1,15901

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 15.7 km from Williamsburg. 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 USC00199972 (Worthington). Public domain.