Monroe County climate

Monroe County Frost Dates and Growing Season

NOAA 1991-2020 normals for Clarendon, 9.4 km from Monroe County, elevation 179 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Clarendon. 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 March 15 and the first fall freeze around November 11, a growing season of about 241 days.

Median at 36°F
last March 29, first November 1
Median at 32°F
last March 15, first November 11
Median at 28°F
last March 2, first November 24

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°FApr 14Apr 7Apr 3Mar 31Mar 29Mar 26Mar 22Mar 17Mar 10
32°FApr 1Mar 27Mar 23Mar 18Mar 15Mar 11Mar 7Mar 3Feb 27
28°FMar 19Mar 14Mar 9Mar 6Mar 2Feb 28Feb 24Feb 18Feb 9
24°FMar 9Mar 3Feb 28Feb 24Feb 18Feb 12Feb 5Jan 31Jan 22
20°FMar 1Feb 24Feb 15Feb 8Feb 3Jan 30Jan 25Jan 17Jan 4
16°FFeb 23Feb 12Feb 4Jan 31Jan 27Jan 21Jan 15Jan 6Dec 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°FOct 19Oct 24Oct 27Oct 30Nov 1Nov 4Nov 7Nov 11Nov 16
32°FOct 28Nov 1Nov 5Nov 8Nov 11Nov 15Nov 19Nov 24Nov 30
28°FNov 5Nov 11Nov 15Nov 20Nov 24Nov 28Dec 1Dec 6Dec 19
24°FNov 16Nov 25Nov 29Dec 4Dec 11Dec 18Dec 25Dec 31Jan 9
20°FDec 1Dec 10Dec 21Dec 27Dec 31Jan 3Jan 10Jan 18Feb 1
16°FDec 16Dec 28Jan 1Jan 5Jan 11Jan 17Jan 23Jan 30Feb 7

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°F242232227222218214209204196
32°F268258250246241236230224216
28°F297286279272267261255248239
24°F330320310303296290283275265
20°F365350341334328322313305291
16°F365365365365358349339332318

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
99% of years
20°F or colder
88% of years
16°F or colder
58% 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
3,230
Cooling degree days, base 65°F
1,993
Growing degree days, base 40°F
8,166
Growing degree days, base 45°F
6,634
Growing degree days, base 50°F
5,256
Growing degree days, base 55°F
4,025
Growing degree days, base 60°F
2,934

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January771126
February586147
March40711160
April16160362
May26203642
June0408858
July0507972
August0465930
September15255690
October14774403
November4348127
December684040

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 9.4 km from Monroe 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 USC00031442 (Clarendon). Public domain.