Hart County climate

Hart County Frost Dates and Growing Season

NOAA 1991-2020 normals for Millerstown 4E, 18.5 km from Hart County, elevation 600 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Millerstown 4E. 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 21 and the first fall freeze around October 18, a growing season of about 178 days.

Median at 36°F
last May 1, first October 10
Median at 32°F
last April 21, first October 18
Median at 28°F
last April 10, first October 26

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 14May 9May 6May 3May 1Apr 29Apr 25Apr 22Apr 17
32°FMay 6May 1Apr 28Apr 24Apr 21Apr 19Apr 16Apr 12Apr 8
28°FApr 26Apr 20Apr 16Apr 13Apr 10Apr 7Apr 5Apr 1Mar 28
24°FApr 13Apr 8Apr 4Apr 2Mar 31Mar 28Mar 24Mar 19Mar 13
20°FApr 4Mar 30Mar 26Mar 22Mar 18Mar 15Mar 11Mar 6Feb 28
16°FMar 25Mar 19Mar 15Mar 11Mar 6Mar 3Feb 28Feb 22Feb 14

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 1Oct 4Oct 6Oct 8Oct 10Oct 12Oct 14Oct 17Oct 20
32°FOct 6Oct 11Oct 14Oct 16Oct 18Oct 20Oct 23Oct 24Oct 28
28°FOct 14Oct 19Oct 22Oct 24Oct 26Oct 29Oct 31Nov 2Nov 6
24°FOct 23Oct 28Oct 31Nov 2Nov 4Nov 7Nov 11Nov 15Nov 21
20°FNov 2Nov 5Nov 10Nov 13Nov 16Nov 20Nov 24Dec 1Dec 6
16°FNov 10Nov 16Nov 21Nov 26Dec 1Dec 3Dec 8Dec 14Dec 22

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°F177171167163160158154150144
32°F196190186181178174170165160
28°F218211206202198194190186179
24°F242234230225220216212207199
20°F270262255250244239234227220
16°F299288280275268263257250241

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
4,792
Cooling degree days, base 65°F
1,088
Growing degree days, base 40°F
6,212
Growing degree days, base 45°F
4,881
Growing degree days, base 50°F
3,718
Growing degree days, base 55°F
2,704
Growing degree days, base 60°F
1,828

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,00307
February821117
March644060
April33113191
May12284433
June12213651
July1329793
August3286749
September53140537
October31222220
November622148
December870013

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 18.5 km from Hart 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 USC00155444 (Millerstown 4E). Public domain.