Washington County climate

Washington County Frost Dates and Growing Season

NOAA 1991-2020 normals for Nashville 1 E, 4.6 km from Washington County, elevation 513 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Nashville 1 E. 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 7 and the first fall freeze around October 26, a growing season of about 201 days.

Median at 36°F
last April 19, first October 16
Median at 32°F
last April 7, first October 26
Median at 28°F
last March 30, 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 4Apr 29Apr 25Apr 22Apr 19Apr 16Apr 13Apr 9Apr 6
32°FApr 22Apr 18Apr 13Apr 10Apr 7Apr 5Apr 2Mar 30Mar 24
28°FApr 12Apr 7Apr 4Apr 1Mar 30Mar 27Mar 23Mar 19Mar 13
24°FApr 3Mar 31Mar 27Mar 22Mar 19Mar 15Mar 11Mar 7Mar 1
20°FMar 26Mar 19Mar 15Mar 12Mar 9Mar 5Mar 2Feb 27Feb 21
16°FMar 17Mar 11Mar 7Mar 3Feb 28Feb 25Feb 21Feb 14Feb 7

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 4Oct 9Oct 12Oct 14Oct 16Oct 19Oct 21Oct 24Oct 27
32°FOct 14Oct 18Oct 22Oct 24Oct 26Oct 28Oct 31Nov 2Nov 6
28°FOct 24Oct 29Nov 1Nov 2Nov 4Nov 7Nov 10Nov 14Nov 19
24°FNov 1Nov 5Nov 9Nov 12Nov 15Nov 18Nov 23Nov 27Dec 2
20°FNov 10Nov 14Nov 18Nov 22Nov 26Nov 29Dec 3Dec 6Dec 13
16°FNov 18Nov 24Nov 28Dec 2Dec 6Dec 10Dec 14Dec 20Dec 27

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°F198192187184180176172167159
32°F219213209205201198194189183
28°F242235229225221218214210202
24°F263257251247243238233228221
20°F287277272267263257252246238
16°F308300293287282277272265257

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
4,859
Cooling degree days, base 65°F
1,304
Growing degree days, base 40°F
6,502
Growing degree days, base 45°F
5,197
Growing degree days, base 50°F
4,027
Growing degree days, base 55°F
2,989
Growing degree days, base 60°F
2,078

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,08505
February857011
March647263
April30217215
May94105478
June7280723
July0380845
August2329792
September47158562
October26433269
November617157
December93809

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 4.6 km from Washington 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 USC00116011 (Nashville 1 E). Public domain.