Perry County climate

Perry County Frost Dates and Growing Season

NOAA 1991-2020 normals for Alum Fk, 18.7 km from Perry County, elevation 698 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Alum Fk. 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 March 28 and the first fall freeze around November 8, a growing season of about 226 days.

Median at 36°F
last April 8, first October 29
Median at 32°F
last March 28, first November 8
Median at 28°F
last March 15, first November 19

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°FApr 25Apr 19Apr 14Apr 11Apr 8Apr 6Apr 2Mar 31Mar 25
32°FApr 12Apr 7Apr 4Apr 1Mar 28Mar 25Mar 20Mar 15Mar 9
28°FApr 2Mar 27Mar 22Mar 17Mar 15Mar 11Mar 6Mar 2Feb 26
24°FMar 21Mar 15Mar 9Mar 5Mar 2Feb 28Feb 24Feb 18Feb 11
20°FMar 10Mar 3Feb 28Feb 23Feb 17Feb 11Feb 4Jan 31Jan 23
16°FFeb 28Feb 19Feb 11Feb 6Feb 1Jan 28Jan 22Jan 17Jan 5

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 16Oct 20Oct 23Oct 26Oct 29Nov 1Nov 3Nov 6Nov 11
32°FOct 26Oct 31Nov 2Nov 5Nov 8Nov 11Nov 15Nov 19Nov 25
28°FNov 3Nov 7Nov 11Nov 15Nov 19Nov 23Nov 26Dec 1Dec 5
24°FNov 12Nov 18Nov 23Nov 26Dec 1Dec 4Dec 9Dec 15Dec 24
20°FNov 22Nov 29Dec 5Dec 11Dec 18Dec 24Dec 29Jan 3Jan 12
16°FDec 8Dec 17Dec 24Dec 29Jan 1Jan 5Jan 11Jan 17Jan 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°F223214210206202197193188181
32°F249241235231226221216211204
28°F273265258253248243238232224
24°F302291283277273268262256247
20°F334322314307303296289281269
16°F363351341334329322315307298

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
99% of years
16°F or colder
90% 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
3,494
Cooling degree days, base 65°F
1,687
Growing degree days, base 40°F
7,656
Growing degree days, base 45°F
6,153
Growing degree days, base 50°F
4,806
Growing degree days, base 55°F
3,616
Growing degree days, base 60°F
2,574

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January806018
February628135
March4466128
April19631301
May47137556
June1325774
July0456921
August0439904
September15235670
October16653364
November4594107
December730029

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 18.7 km from Perry County. 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 USC00030130 (Alum Fk). Public domain.