Greenback climate

Greenback Frost Dates and Growing Season

NOAA 1991-2020 normals for Lenoir City, 16.3 km from Greenback, elevation 785 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Lenoir City. 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 5 and the first fall freeze around November 1, a growing season of about 210 days.

Median at 36°F
last April 18, first October 25
Median at 32°F
last April 5, first November 1
Median at 28°F
last March 25, first November 12

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 5Apr 29Apr 25Apr 21Apr 18Apr 15Apr 12Apr 8Apr 3
32°FApr 21Apr 16Apr 12Apr 8Apr 5Apr 2Mar 30Mar 25Mar 19
28°FApr 9Apr 4Apr 1Mar 28Mar 25Mar 20Mar 17Mar 12Mar 6
24°FMar 30Mar 24Mar 18Mar 14Mar 10Mar 6Mar 1Feb 25Feb 16
20°FMar 18Mar 11Mar 4Feb 28Feb 23Feb 17Feb 10Feb 4Jan 29
16°FMar 6Feb 28Feb 20Feb 11Feb 4Feb 1Jan 28Jan 20Jan 10

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 12Oct 17Oct 20Oct 23Oct 25Oct 27Oct 30Nov 1Nov 5
32°FOct 20Oct 25Oct 28Oct 31Nov 1Nov 4Nov 7Nov 10Nov 15
28°FOct 31Nov 3Nov 6Nov 9Nov 12Nov 15Nov 19Nov 24Dec 1
24°FNov 8Nov 13Nov 17Nov 23Nov 27Dec 1Dec 4Dec 8Dec 19
20°FNov 21Nov 29Dec 3Dec 7Dec 13Dec 20Dec 26Jan 1Jan 9
16°FDec 6Dec 13Dec 22Dec 28Jan 1Jan 5Jan 11Jan 18Jan 28

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°F208202197192188183178173166
32°F231225218214210206202197189
28°F258250244238233228223216209
24°F291281272266261255249242234
20°F325316307300294288280274262
16°F356341334330324316308300289

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
92% 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
3,654
Cooling degree days, base 65°F
1,536
Growing degree days, base 40°F
7,362
Growing degree days, base 45°F
5,878
Growing degree days, base 50°F
4,556
Growing degree days, base 55°F
3,395
Growing degree days, base 60°F
2,392

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January828017
February647025
March4773110
April22528278
May63128531
June3303750
July0420885
August0391856
September16221656
October18740332
November485289
December724028

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 16.3 km from Greenback. 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 USC00405158 (Lenoir City). Public domain.