Marshall County climate

Marshall County Frost Dates and Growing Season

NOAA 1991-2020 normals for Benton, 3 km from Marshall County, elevation 365 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Benton. 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 9 and the first fall freeze around October 19, a growing season of about 192 days.

Median at 36°F
last April 24, first October 10
Median at 32°F
last April 9, first October 19
Median at 28°F
last March 31, first October 28

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 28Apr 24Apr 20Apr 16Apr 13Apr 8
32°FApr 28Apr 21Apr 17Apr 12Apr 9Apr 6Apr 4Mar 31Mar 27
28°FApr 14Apr 9Apr 5Apr 2Mar 31Mar 28Mar 24Mar 19Mar 15
24°FApr 3Mar 30Mar 26Mar 22Mar 18Mar 15Mar 11Mar 6Mar 1
20°FMar 22Mar 17Mar 13Mar 9Mar 6Mar 3Feb 28Feb 22Feb 12
16°FMar 15Mar 9Mar 4Mar 1Feb 25Feb 19Feb 13Feb 6Jan 30

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°FSep 29Oct 3Oct 5Oct 8Oct 10Oct 13Oct 16Oct 18Oct 22
32°FOct 6Oct 11Oct 14Oct 17Oct 19Oct 21Oct 24Oct 26Oct 29
28°FOct 15Oct 20Oct 23Oct 26Oct 28Oct 31Nov 2Nov 6Nov 11
24°FOct 27Nov 1Nov 3Nov 6Nov 9Nov 13Nov 16Nov 22Nov 30
20°FNov 5Nov 11Nov 15Nov 18Nov 23Nov 27Dec 1Dec 5Dec 12
16°FNov 14Nov 21Nov 26Dec 1Dec 5Dec 10Dec 15Dec 22Dec 29

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°F189182177173170165161156150
32°F209204199196192188183178172
28°F235227221217212209205201194
24°F262253247243238232227221214
20°F291281273268264258252246238
16°F319307301295288280274266257

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
4,262
Cooling degree days, base 65°F
1,329
Growing degree days, base 40°F
6,822
Growing degree days, base 45°F
5,412
Growing degree days, base 50°F
4,147
Growing degree days, base 55°F
3,054
Growing degree days, base 60°F
2,120

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January94807
February763022
March551381
April24923247
May7999487
June2278726
July0377841
August0352816
September36169584
October25128259
November548265
December835013

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 3 km from Marshall 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 USC00150611 (Benton). Public domain.