Clay County climate

Clay County Frost Dates and Growing Season

NOAA 1991-2020 normals for Murphy 4ESE, 19.9 km from Clay County, elevation 1600 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Murphy 4ESE. 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 22 and the first fall freeze around October 20, a growing season of about 180 days.

Median at 36°F
last May 4, first October 13
Median at 32°F
last April 22, first October 20
Median at 28°F
last April 9, 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 18May 13May 9May 6May 4May 1Apr 29Apr 24Apr 19
32°FMay 7May 2Apr 30Apr 25Apr 22Apr 19Apr 15Apr 12Apr 7
28°FApr 27Apr 22Apr 17Apr 13Apr 9Apr 6Apr 2Mar 29Mar 21
24°FApr 14Apr 7Apr 3Mar 31Mar 28Mar 24Mar 19Mar 12Mar 4
20°FApr 1Mar 27Mar 22Mar 16Mar 11Mar 5Feb 28Feb 24Feb 14
16°FMar 21Mar 13Mar 6Feb 28Feb 24Feb 17Feb 11Feb 4Jan 28

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 1Oct 5Oct 8Oct 10Oct 13Oct 15Oct 18Oct 21Oct 26
32°FOct 8Oct 12Oct 15Oct 18Oct 20Oct 23Oct 26Oct 29Nov 2
28°FOct 16Oct 21Oct 24Oct 27Oct 30Nov 1Nov 4Nov 8Nov 14
24°FOct 28Nov 1Nov 3Nov 6Nov 10Nov 13Nov 17Nov 21Nov 29
20°FNov 7Nov 12Nov 16Nov 21Nov 25Nov 29Dec 2Dec 7Dec 17
16°FNov 18Nov 24Dec 1Dec 4Dec 8Dec 15Dec 22Dec 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°F179172168165161157154149142
32°F200193188184180176173167160
28°F229220214209204200194190182
24°F257247242235230226221215208
20°F295282273266260254247240232
16°F330317307300293285277268257

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
4,041
Cooling degree days, base 65°F
1,038
Growing degree days, base 40°F
6,556
Growing degree days, base 45°F
5,112
Growing degree days, base 50°F
3,839
Growing degree days, base 55°F
2,742
Growing degree days, base 60°F
1,809

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January851015
February679019
March537180
April28212218
May10072440
June11201640
July0307772
August1284749
September33139557
October25020261
November538166
December758024

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 19.9 km from Clay 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 USC00316001 (Murphy 4ESE). Public domain.