Harmony climate

Harmony Frost Dates and Growing Season

NOAA 1991-2020 normals for Statesville 2 Nne, 19 km from Harmony, elevation 803 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Statesville 2 Nne. 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 16 and the first fall freeze around October 25, a growing season of about 191 days.

Median at 36°F
last April 28, first October 17
Median at 32°F
last April 16, first October 25
Median at 28°F
last April 3, first November 3

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 12May 7May 3Apr 30Apr 28Apr 24Apr 21Apr 18Apr 12
32°FMay 1Apr 25Apr 21Apr 18Apr 16Apr 13Apr 10Apr 6Apr 2
28°FApr 17Apr 12Apr 9Apr 6Apr 3Apr 1Mar 28Mar 23Mar 17
24°FApr 5Apr 1Mar 28Mar 25Mar 21Mar 17Mar 13Mar 8Feb 28
20°FMar 26Mar 21Mar 16Mar 11Mar 7Mar 3Feb 27Feb 22Feb 12
16°FMar 15Mar 8Mar 3Feb 27Feb 20Feb 14Feb 7Jan 31Jan 23

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 8Oct 11Oct 14Oct 17Oct 19Oct 22Oct 24Oct 29
32°FOct 13Oct 17Oct 21Oct 23Oct 25Oct 28Oct 31Nov 2Nov 5
28°FOct 23Oct 27Oct 30Nov 1Nov 3Nov 5Nov 8Nov 12Nov 18
24°FNov 1Nov 4Nov 7Nov 11Nov 14Nov 17Nov 20Nov 25Dec 1
20°FNov 10Nov 15Nov 20Nov 24Nov 29Dec 1Dec 5Dec 12Dec 23
16°FNov 23Dec 1Dec 5Dec 11Dec 17Dec 24Dec 30Jan 4Jan 13

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°F190183179175171167163157149
32°F211205199195191188184179173
28°F234227222218214210207202196
24°F264256250244238234229224216
20°F298287279273266261256249240
16°F335323314306300293286278267

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
99% 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
3,994
Cooling degree days, base 65°F
1,257
Growing degree days, base 40°F
6,795
Growing degree days, base 45°F
5,369
Growing degree days, base 50°F
4,103
Growing degree days, base 55°F
3,000
Growing degree days, base 60°F
2,049

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January850013
February682020
March541182
April26320240
May8399482
June7256699
July0374839
August1322786
September31158578
October23225276
November537268
December768122

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 19 km from Harmony. 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 USC00318292 (Statesville 2 Nne). Public domain.