Grayson climate

Grayson Frost Dates and Growing Season

NOAA 1991-2020 normals for Grayson 2 E, 3.5 km from Grayson, elevation 580 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Grayson 2 E. 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 27 and the first fall freeze around October 17, a growing season of about 172 days.

Median at 36°F
last May 7, first October 7
Median at 32°F
last April 27, first October 17
Median at 28°F
last April 15, first October 26

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 21May 17May 13May 10May 7May 3Apr 30Apr 27Apr 22
32°FMay 15May 9May 4Apr 30Apr 27Apr 24Apr 21Apr 18Apr 14
28°FMay 5Apr 27Apr 22Apr 19Apr 15Apr 13Apr 9Apr 5Mar 31
24°FApr 18Apr 12Apr 8Apr 4Apr 1Mar 30Mar 27Mar 22Mar 16
20°FApr 5Mar 31Mar 28Mar 25Mar 22Mar 18Mar 14Mar 10Mar 3
16°FMar 27Mar 20Mar 17Mar 12Mar 8Mar 4Feb 28Feb 23Feb 12

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 27Oct 1Oct 4Oct 5Oct 7Oct 10Oct 13Oct 16Oct 20
32°FOct 6Oct 9Oct 12Oct 15Oct 17Oct 19Oct 22Oct 25Oct 29
28°FOct 14Oct 18Oct 21Oct 24Oct 26Oct 29Nov 1Nov 3Nov 8
24°FOct 23Oct 27Oct 31Nov 1Nov 4Nov 7Nov 10Nov 14Nov 19
20°FNov 1Nov 5Nov 8Nov 12Nov 15Nov 20Nov 25Nov 30Dec 6
16°FNov 10Nov 16Nov 22Nov 27Dec 1Dec 4Dec 10Dec 17Dec 24

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°F172166162158155151147142137
32°F191185180176172169165160154
28°F214207202197193189185180171
24°F240232227222218214210203196
20°F267258252246241236231225218
16°F297288280274267261256249241

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
4,952
Cooling degree days, base 65°F
980
Growing degree days, base 40°F
5,981
Growing degree days, base 45°F
4,680
Growing degree days, base 50°F
3,536
Growing degree days, base 55°F
2,540
Growing degree days, base 60°F
1,687

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,01009
February83208
March687251
April35413178
May13967398
June17196630
July1305769
August2267730
September60117508
October32613200
November636042
December890014

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 3.5 km from Grayson. 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 USC00153389 (Grayson 2 E). Public domain.