Red Jacket climate

Red Jacket Frost Dates and Growing Season

NOAA 1991-2020 normals for Williamson, 12.3 km from Red Jacket, elevation 760 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Williamson. 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 8 and the first fall freeze around November 2, a growing season of about 206 days.

Median at 36°F
last April 22, first October 25
Median at 32°F
last April 8, first November 2
Median at 28°F
last March 29, first November 10

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 8May 3Apr 29Apr 24Apr 22Apr 19Apr 16Apr 13Apr 8
32°FApr 25Apr 19Apr 15Apr 12Apr 8Apr 5Apr 2Mar 31Mar 26
28°FApr 12Apr 5Apr 2Mar 31Mar 29Mar 25Mar 22Mar 17Mar 10
24°FMar 31Mar 27Mar 23Mar 19Mar 16Mar 11Mar 7Mar 1Feb 22
20°FMar 22Mar 16Mar 10Mar 6Mar 2Feb 26Feb 21Feb 13Feb 4
16°FMar 15Mar 5Feb 28Feb 21Feb 14Feb 8Feb 3Jan 31Jan 22

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 12Oct 16Oct 19Oct 22Oct 25Oct 27Oct 29Nov 1Nov 5
32°FOct 21Oct 26Oct 29Nov 1Nov 2Nov 4Nov 6Nov 9Nov 13
28°FOct 31Nov 2Nov 5Nov 8Nov 10Nov 13Nov 15Nov 19Nov 26
24°FNov 8Nov 12Nov 15Nov 19Nov 23Nov 27Dec 1Dec 5Dec 14
20°FNov 16Nov 23Nov 29Dec 2Dec 7Dec 13Dec 20Dec 26Jan 1
16°FDec 1Dec 9Dec 16Dec 22Dec 27Jan 1Jan 5Jan 12Jan 19

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°F202196192189184180176171164
32°F225218213210206203199193183
28°F249242236232228224220215208
24°F282271265259254249244238230
20°F315302295287281275269262253
16°F339330323316308303297290280

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
99% 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
4,016
Cooling degree days, base 65°F
1,397
Growing degree days, base 40°F
7,013
Growing degree days, base 45°F
5,589
Growing degree days, base 50°F
4,311
Growing degree days, base 55°F
3,193
Growing degree days, base 60°F
2,226

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January894016
February705021
March559489
April25129262
May80119505
June5272717
July0389854
August1360825
September22190618
October21632300
November513281
December770024

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 12.3 km from Red Jacket. 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 USC00469610 (Williamson). Public domain.