Powell County climate

Powell County Frost Dates and Growing Season

NOAA 1991-2020 normals for Stanton 2W, 7.2 km from Powell County, elevation 720 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Stanton 2W. 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 19 and the first fall freeze around October 20, a growing season of about 184 days.

Median at 36°F
last April 29, first October 13
Median at 32°F
last April 19, first October 20
Median at 28°F
last April 6, first October 30

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 15May 10May 6May 2Apr 29Apr 26Apr 22Apr 20Apr 16
32°FMay 5Apr 30Apr 25Apr 22Apr 19Apr 16Apr 13Apr 9Apr 4
28°FApr 23Apr 17Apr 13Apr 9Apr 6Apr 3Apr 1Mar 30Mar 22
24°FApr 10Apr 4Apr 1Mar 30Mar 27Mar 24Mar 20Mar 16Mar 10
20°FMar 30Mar 26Mar 22Mar 17Mar 14Mar 11Mar 7Mar 2Feb 23
16°FMar 22Mar 16Mar 13Mar 8Mar 5Mar 1Feb 24Feb 16Feb 7

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 2Oct 6Oct 8Oct 10Oct 13Oct 15Oct 17Oct 20Oct 23
32°FOct 10Oct 13Oct 16Oct 18Oct 20Oct 22Oct 24Oct 27Oct 31
28°FOct 17Oct 21Oct 24Oct 27Oct 30Nov 1Nov 4Nov 7Nov 13
24°FOct 29Nov 1Nov 4Nov 7Nov 10Nov 13Nov 17Nov 22Nov 29
20°FNov 7Nov 12Nov 15Nov 19Nov 23Nov 27Dec 1Dec 5Dec 11
16°FNov 15Nov 23Nov 28Dec 1Dec 5Dec 11Dec 16Dec 22Dec 30

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°F181176173169166162158153146
32°F203197192188184180176171163
28°F226219214209206201197191183
24°F256245239234229224220215207
20°F282273266260255250245238231
16°F308299293286280274268260252

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
4,735
Cooling degree days, base 65°F
981
Growing degree days, base 40°F
6,165
Growing degree days, base 45°F
4,823
Growing degree days, base 50°F
3,637
Growing degree days, base 55°F
2,604
Growing degree days, base 60°F
1,718

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January995012
February803121
March641367
April33015201
May12877421
June11195635
July2293756
August3247708
September54130527
October30720219
November596154
December865017

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 7.2 km from Powell County. 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 USC00157652 (Stanton 2W). Public domain.