Grafton climate

Grafton Frost Dates and Growing Season

NOAA 1991-2020 normals for Tygart Dam, 3.2 km from Grafton, elevation 1235 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Tygart Dam. 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 April 26 and the first fall freeze around October 22, a growing season of about 178 days.

Median at 36°F
last May 6, first October 12
Median at 32°F
last April 26, first October 22
Median at 28°F
last April 12, first November 1

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 24May 18May 14May 9May 6May 3Apr 30Apr 27Apr 23
32°FMay 14May 6May 3Apr 30Apr 26Apr 23Apr 21Apr 17Apr 12
28°FMay 1Apr 23Apr 19Apr 15Apr 12Apr 9Apr 6Apr 3Mar 31
24°FApr 13Apr 8Apr 5Apr 3Apr 1Mar 30Mar 25Mar 21Mar 15
20°FApr 2Mar 30Mar 26Mar 22Mar 19Mar 16Mar 12Mar 8Mar 2
16°FMar 25Mar 19Mar 15Mar 12Mar 8Mar 5Mar 2Feb 27Feb 19

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 1Oct 4Oct 6Oct 9Oct 12Oct 14Oct 17Oct 21Oct 24
32°FOct 10Oct 14Oct 17Oct 20Oct 22Oct 25Oct 27Oct 30Nov 3
28°FOct 19Oct 24Oct 27Oct 30Nov 1Nov 3Nov 5Nov 9Nov 15
24°FOct 31Nov 3Nov 5Nov 8Nov 11Nov 15Nov 18Nov 23Nov 30
20°FNov 6Nov 11Nov 14Nov 18Nov 23Nov 27Dec 1Dec 6Dec 13
16°FNov 15Nov 22Nov 28Dec 2Dec 7Dec 13Dec 19Dec 25Dec 31

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°F176170165161158153150144136
32°F196191186182178174169164157
28°F222215210205202197193189181
24°F248240235230225221217212207
20°F274267260255249245240234226
16°F301291284277273268263256247

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
5,493
Cooling degree days, base 65°F
600
Growing degree days, base 40°F
5,291
Growing degree days, base 45°F
4,049
Growing degree days, base 50°F
2,957
Growing degree days, base 55°F
2,014
Growing degree days, base 60°F
1,222

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,08604
February91008
March763133
April4165138
May18838327
June39107518
July6201660
August9170626
September8769434
October37210168
November672032
December94409

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 3.2 km from Grafton. 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 USC00468986 (Tygart Dam). Public domain.