Carter County climate

Carter County Frost Dates and Growing Season

NOAA 1991-2020 normals for Clearwater Dam, 26.9 km from Carter County, elevation 660 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Clearwater Dam. 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 9 and the first fall freeze around October 26, a growing season of about 199 days.

Median at 36°F
last April 21, first October 17
Median at 32°F
last April 9, first October 26
Median at 28°F
last March 28, first November 4

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 5May 1Apr 27Apr 24Apr 21Apr 18Apr 15Apr 11Apr 6
32°FApr 24Apr 20Apr 16Apr 12Apr 9Apr 5Apr 2Mar 30Mar 24
28°FApr 13Apr 6Apr 3Mar 31Mar 28Mar 24Mar 21Mar 16Mar 10
24°FMar 31Mar 28Mar 23Mar 19Mar 15Mar 12Mar 8Mar 4Feb 28
20°FMar 21Mar 16Mar 11Mar 7Mar 4Mar 1Feb 26Feb 21Feb 13
16°FMar 14Mar 7Mar 3Feb 28Feb 24Feb 19Feb 13Feb 8Jan 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 5Oct 9Oct 12Oct 15Oct 17Oct 19Oct 21Oct 24Oct 27
32°FOct 12Oct 18Oct 21Oct 24Oct 26Oct 28Oct 30Nov 1Nov 7
28°FOct 23Oct 28Oct 31Nov 1Nov 4Nov 7Nov 10Nov 14Nov 21
24°FNov 1Nov 5Nov 8Nov 11Nov 15Nov 19Nov 24Nov 29Dec 4
20°FNov 8Nov 14Nov 20Nov 24Nov 29Dec 2Dec 6Dec 12Dec 21
16°FNov 18Nov 26Dec 1Dec 6Dec 12Dec 18Dec 23Dec 29Jan 5

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°F197190186181178174170164158
32°F221213208203199195191186179
28°F245237231226222217213207199
24°F269260254249244239233228220
20°F294284278272267262256250242
16°F320309302297291286278271260

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
4,452
Cooling degree days, base 65°F
1,392
Growing degree days, base 40°F
6,757
Growing degree days, base 45°F
5,394
Growing degree days, base 50°F
4,179
Growing degree days, base 55°F
3,107
Growing degree days, base 60°F
2,178

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January98708
February765017
March575381
April27224243
May85108490
June5284729
July0420885
August2367831
September44155562
October26228259
November573264
December882012

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 26.9 km from Carter 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 USC00231674 (Clearwater Dam). Public domain.