Perry County climate

Perry County Frost Dates and Growing Season

NOAA 1991-2020 normals for Skyline 1 Se, 26.7 km from Perry County, elevation 1083 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Skyline 1 Se. 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 18 and the first fall freeze around October 28, a growing season of about 191 days.

Median at 36°F
last April 29, first October 20
Median at 32°F
last April 18, first October 28
Median at 28°F
last April 6, first November 5

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 13May 7May 3Apr 30Apr 29Apr 26Apr 23Apr 20Apr 17
32°FMay 2Apr 27Apr 23Apr 21Apr 18Apr 16Apr 14Apr 11Apr 6
28°FApr 20Apr 16Apr 13Apr 9Apr 6Apr 4Apr 1Mar 30Mar 24
24°FApr 10Apr 5Apr 1Mar 30Mar 27Mar 23Mar 19Mar 15Mar 7
20°FMar 31Mar 26Mar 21Mar 17Mar 14Mar 9Mar 4Feb 28Feb 18
16°FMar 21Mar 15Mar 10Mar 4Feb 27Feb 20Feb 12Feb 6Jan 31

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 9Oct 13Oct 15Oct 18Oct 20Oct 21Oct 23Oct 25Oct 28
32°FOct 17Oct 22Oct 24Oct 26Oct 28Oct 30Nov 1Nov 3Nov 7
28°FOct 27Oct 31Nov 1Nov 3Nov 5Nov 7Nov 9Nov 13Nov 18
24°FNov 3Nov 5Nov 8Nov 11Nov 13Nov 17Nov 20Nov 25Dec 1
20°FNov 8Nov 13Nov 17Nov 21Nov 25Nov 30Dec 3Dec 8Dec 18
16°FNov 18Nov 26Dec 1Dec 5Dec 11Dec 18Dec 24Dec 30Jan 8

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°F188184180176173169166162156
32°F207200197194191188185181174
28°F231224220216213210206202197
24°F260250243238233229225220214
20°F289278270264257252246239232
16°F323310302295289282275267255

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
4,287
Cooling degree days, base 65°F
1,043
Growing degree days, base 40°F
6,446
Growing degree days, base 45°F
5,041
Growing degree days, base 50°F
3,809
Growing degree days, base 55°F
2,741
Growing degree days, base 60°F
1,817

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January914011
February725016
March589172
April29413218
May10279446
June9197639
July1306770
August1292756
September41131540
October24823264
November565158
December800018

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 26.7 km from Perry 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 USC00157431 (Skyline 1 Se). Public domain.