Carroll County climate

Carroll County Frost Dates and Growing Season

NOAA 1991-2020 normals for Carroll, 3.4 km from Carroll County, elevation 1240 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Carroll. 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 27 and the first fall freeze around October 10, a growing season of about 166 days.

Median at 36°F
last May 6, first September 30
Median at 32°F
last April 27, first October 10
Median at 28°F
last April 16, first October 21

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 17May 13May 10May 8May 6May 4May 1Apr 28Apr 23
32°FMay 8May 5May 2Apr 30Apr 27Apr 24Apr 21Apr 18Apr 14
28°FApr 29Apr 25Apr 22Apr 19Apr 16Apr 13Apr 10Apr 7Apr 3
24°FApr 21Apr 16Apr 12Apr 9Apr 6Apr 4Apr 1Mar 30Mar 24
20°FApr 12Apr 7Apr 3Apr 1Mar 31Mar 27Mar 23Mar 18Mar 12
16°FApr 5Mar 31Mar 28Mar 23Mar 20Mar 16Mar 12Mar 9Mar 4

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 17Sep 21Sep 24Sep 27Sep 30Oct 1Oct 5Oct 9Oct 14
32°FSep 25Sep 29Oct 2Oct 6Oct 10Oct 13Oct 16Oct 20Oct 24
28°FOct 5Oct 12Oct 16Oct 19Oct 21Oct 24Oct 26Oct 29Nov 3
24°FOct 17Oct 22Oct 26Oct 28Oct 31Nov 2Nov 4Nov 8Nov 13
20°FOct 26Oct 30Nov 2Nov 5Nov 7Nov 10Nov 13Nov 17Nov 23
16°FNov 3Nov 7Nov 10Nov 13Nov 16Nov 20Nov 24Nov 28Dec 2

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°F165159155151147144140135129
32°F185178174169166163159153145
28°F207199195191187183179174168
24°F226217213209205202197193186
20°F244237230226221217214209202
16°F262254249245241235230224217

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
6,921
Cooling degree days, base 65°F
866
Growing degree days, base 40°F
5,154
Growing degree days, base 45°F
4,061
Growing degree days, base 50°F
3,081
Growing degree days, base 55°F
2,218
Growing degree days, base 60°F
1,477

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,42300
February1,16201
March908121
April515595
May20555332
June26195620
July4286747
August12220673
September12091428
October44013147
November854019
December1,25201

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 3.4 km from Carroll 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 USC00131233 (Carroll). Public domain.