Roane County climate

Roane County Frost Dates and Growing Season

NOAA 1991-2020 normals for Kingston, 1.1 km from Roane County, elevation 814 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Kingston. 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 3 and the first fall freeze around November 4, a growing season of about 215 days.

Median at 36°F
last April 17, first October 26
Median at 32°F
last April 3, first November 4
Median at 28°F
last March 20, first November 15

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 4Apr 29Apr 24Apr 20Apr 17Apr 14Apr 10Apr 6Mar 31
32°FApr 20Apr 14Apr 9Apr 6Apr 3Mar 31Mar 28Mar 23Mar 16
28°FApr 5Mar 31Mar 28Mar 24Mar 20Mar 17Mar 14Mar 8Mar 2
24°FMar 27Mar 20Mar 16Mar 12Mar 8Mar 4Feb 28Feb 24Feb 17
20°FMar 17Mar 9Mar 4Feb 28Feb 24Feb 18Feb 10Feb 4Jan 26
16°FMar 6Feb 28Feb 20Feb 12Feb 7Feb 1Jan 28Jan 20Jan 11

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 13Oct 18Oct 21Oct 24Oct 26Oct 28Oct 31Nov 2Nov 6
32°FOct 23Oct 28Oct 31Nov 1Nov 4Nov 7Nov 9Nov 13Nov 18
28°FNov 3Nov 7Nov 10Nov 12Nov 15Nov 19Nov 23Nov 27Dec 3
24°FNov 11Nov 16Nov 21Nov 25Nov 30Dec 3Dec 7Dec 14Dec 24
20°FNov 25Dec 1Dec 6Dec 12Dec 18Dec 23Dec 28Jan 2Jan 12
16°FDec 11Dec 19Dec 26Dec 29Jan 1Jan 6Jan 11Jan 19Jan 29

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°F212205200196192187183178172
32°F236230223219215211207202194
28°F265256251244240235231225218
24°F295286278272267262256249242
20°F327316308302297291284277268
16°F358343334329323315307300290

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
93% 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
3,832
Cooling degree days, base 65°F
1,460
Growing degree days, base 40°F
7,160
Growing degree days, base 45°F
5,708
Growing degree days, base 50°F
4,414
Growing degree days, base 55°F
3,285
Growing degree days, base 60°F
2,303

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January865013
February678019
March503293
April23525267
May63122525
June2290738
July0398863
August0371835
September17213646
October19537323
November508171
December766020

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 1.1 km from Roane 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 USC00404871 (Kingston). Public domain.