Monroe County climate

Monroe County Frost Dates and Growing Season

NOAA 1991-2020 normals for Thomaston 4SE, 36.2 km from Monroe County, elevation 620 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Thomaston 4SE. 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 23 and the first fall freeze around November 12, a growing season of about 234 days.

Median at 36°F
last April 5, first November 1
Median at 32°F
last March 23, first November 12
Median at 28°F
last March 10, first November 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°FApr 20Apr 15Apr 11Apr 8Apr 5Apr 3Mar 30Mar 26Mar 19
32°FApr 11Apr 4Mar 31Mar 27Mar 23Mar 19Mar 15Mar 11Mar 1
28°FMar 29Mar 22Mar 17Mar 14Mar 10Mar 5Feb 28Feb 24Feb 14
24°FMar 17Mar 11Mar 5Feb 28Feb 24Feb 17Feb 10Feb 1Jan 24
20°FMar 5Feb 27Feb 17Feb 10Feb 3Jan 30Jan 23Jan 16Jan 5
16°FFeb 19Feb 8Jan 31Jan 27Jan 22Jan 17Jan 11Jan 4Dec 29

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 20Oct 24Oct 27Oct 30Nov 1Nov 3Nov 6Nov 9Nov 16
32°FOct 31Nov 3Nov 5Nov 8Nov 12Nov 15Nov 18Nov 22Nov 28
28°FNov 7Nov 13Nov 17Nov 22Nov 26Dec 1Dec 3Dec 8Dec 18
24°FNov 24Dec 1Dec 4Dec 8Dec 13Dec 20Dec 26Jan 1Jan 8
20°FDec 7Dec 13Dec 21Dec 28Jan 1Jan 4Jan 9Jan 17Jan 30
16°FDec 15Dec 24Dec 31Jan 3Jan 7Jan 13Jan 19Jan 25Feb 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°F232224219215211207202198191
32°F257249243239234230225219212
28°F292281274267260255249243235
24°F328315309300295287279272260
20°F362348339332325316309303292
16°F365365365362352342334327313

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
92% of years
16°F or colder
61% 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
2,463
Cooling degree days, base 65°F
1,935
Growing degree days, base 40°F
8,692
Growing degree days, base 45°F
7,027
Growing degree days, base 50°F
5,500
Growing degree days, base 55°F
4,137
Growing degree days, base 60°F
2,948

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January600050
February464277
March31510203
April12156392
May17195643
June1365814
July0468933
August0449914
September5291736
October8385469
November31914192
December540176

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 36.2 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 USC00098661 (Thomaston 4SE). Public domain.