Hermitage climate

Hermitage Frost Dates and Growing Season

NOAA 1991-2020 normals for Old Hickory WFO, 7.7 km from Hermitage, elevation 590 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Old Hickory WFO. 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 1 and the first fall freeze around November 4, a growing season of about 216 days.

Median at 36°F
last April 13, first October 26
Median at 32°F
last April 1, 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°FApr 30Apr 24Apr 21Apr 17Apr 13Apr 10Apr 7Apr 3Mar 29
32°FApr 17Apr 10Apr 7Apr 3Apr 1Mar 29Mar 26Mar 21Mar 17
28°FApr 6Apr 1Mar 28Mar 24Mar 20Mar 17Mar 12Mar 8Mar 2
24°FMar 28Mar 21Mar 16Mar 11Mar 7Mar 4Feb 28Feb 25Feb 19
20°FMar 15Mar 8Mar 3Feb 28Feb 26Feb 21Feb 16Feb 10Feb 3
16°FMar 7Feb 28Feb 24Feb 18Feb 13Feb 8Feb 2Jan 30Jan 19

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 15Oct 19Oct 21Oct 24Oct 26Oct 29Oct 31Nov 3Nov 7
32°FOct 23Oct 27Oct 31Nov 1Nov 4Nov 6Nov 10Nov 14Nov 20
28°FNov 2Nov 5Nov 8Nov 12Nov 15Nov 19Nov 23Nov 27Dec 2
24°FNov 9Nov 14Nov 18Nov 22Nov 26Dec 1Dec 4Dec 8Dec 16
20°FNov 20Nov 27Dec 1Dec 5Dec 10Dec 14Dec 21Dec 25Jan 2
16°FDec 2Dec 10Dec 17Dec 24Dec 28Jan 1Jan 5Jan 11Jan 19

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°F215208204199195190186182175
32°F239231225221216212209205198
28°F265258251247241236231225219
24°F288280273268262258253247239
20°F317306300295288282277270261
16°F341331324318312306301295284

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
98% 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
3,825
Cooling degree days, base 65°F
1,542
Growing degree days, base 40°F
7,319
Growing degree days, base 45°F
5,866
Growing degree days, base 50°F
4,558
Growing degree days, base 55°F
3,402
Growing degree days, base 60°F
2,396

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January869019
February688028
March5086110
April22734285
May67130529
June4300747
July0417882
August0389854
September22215643
October19546333
November491398
December755030

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 7.7 km from Hermitage. 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 USC00406806 (Old Hickory WFO). Public domain.