Marshall County climate

Marshall County Frost Dates and Growing Season

NOAA 1991-2020 normals for Lewisburg Exp Stn, 7.3 km from Marshall County, elevation 787 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Lewisburg Exp Stn. 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 14 and the first fall freeze around October 22, a growing season of about 192 days.

Median at 36°F
last April 26, first October 13
Median at 32°F
last April 14, first October 22
Median at 28°F
last April 3, first November 2

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 11May 5May 1Apr 29Apr 26Apr 23Apr 19Apr 16Apr 10
32°FApr 30Apr 26Apr 22Apr 18Apr 14Apr 11Apr 8Apr 5Mar 31
28°FApr 20Apr 13Apr 9Apr 6Apr 3Mar 31Mar 28Mar 23Mar 16
24°FApr 10Apr 5Mar 31Mar 28Mar 24Mar 19Mar 15Mar 7Feb 28
20°FMar 31Mar 25Mar 19Mar 14Mar 9Mar 3Feb 26Feb 21Feb 11
16°FMar 18Mar 11Mar 4Feb 27Feb 22Feb 17Feb 11Feb 4Jan 28

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 7Oct 10Oct 13Oct 16Oct 18Oct 21Oct 26
32°FOct 9Oct 14Oct 18Oct 20Oct 22Oct 25Oct 28Nov 1Nov 5
28°FOct 18Oct 22Oct 27Oct 31Nov 2Nov 5Nov 8Nov 12Nov 17
24°FOct 29Nov 3Nov 6Nov 10Nov 14Nov 17Nov 21Nov 27Dec 4
20°FNov 6Nov 12Nov 17Nov 22Nov 27Dec 1Dec 4Dec 10Dec 21
16°FNov 20Nov 29Dec 2Dec 7Dec 13Dec 21Dec 26Jan 1Jan 11

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°F190183178174170165161155148
32°F213206201196192187182177169
28°F238229222217213209204199190
24°F263254247241236230224218210
20°F298285276269263257251244234
16°F331317308301295288282274260

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
3,714
Cooling degree days, base 65°F
1,568
Growing degree days, base 40°F
7,396
Growing degree days, base 45°F
5,919
Growing degree days, base 50°F
4,591
Growing degree days, base 55°F
3,425
Growing degree days, base 60°F
2,419

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January828023
February646136
March4895114
April23433277
May65140540
June3315762
July0428893
August1387851
September27210633
October20444325
November4834102
December734035

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 7.3 km from Marshall 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 USC00405187 (Lewisburg Exp Stn). Public domain.