Franklin County climate

Franklin County Frost Dates and Growing Season

NOAA 1991-2020 normals for Russellville #2, 12.8 km from Franklin County, elevation 830 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Russellville #2. 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 31 and the first fall freeze around November 4, a growing season of about 221 days.

Median at 36°F
last April 11, first October 26
Median at 32°F
last March 31, first November 4
Median at 28°F
last March 17, first November 16

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 30Apr 24Apr 19Apr 15Apr 11Apr 8Apr 5Apr 1Mar 27
32°FApr 16Apr 9Apr 6Apr 3Mar 31Mar 27Mar 24Mar 18Mar 13
28°FApr 3Mar 30Mar 26Mar 20Mar 17Mar 13Mar 8Mar 3Feb 26
24°FMar 24Mar 17Mar 12Mar 8Mar 4Feb 28Feb 23Feb 16Feb 3
20°FMar 15Mar 7Mar 2Feb 26Feb 19Feb 12Feb 3Jan 28Jan 16
16°FMar 7Feb 28Feb 17Feb 9Feb 1Jan 28Jan 21Jan 14Jan 3

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 13Oct 17Oct 20Oct 23Oct 26Oct 29Nov 1Nov 4Nov 9
32°FOct 21Oct 27Oct 30Nov 1Nov 4Nov 7Nov 12Nov 17Nov 24
28°FNov 1Nov 4Nov 7Nov 12Nov 16Nov 19Nov 24Nov 30Dec 5
24°FNov 8Nov 15Nov 20Nov 25Dec 1Dec 3Dec 7Dec 16Dec 27
20°FNov 20Nov 28Dec 2Dec 8Dec 16Dec 24Jan 1Jan 7Jan 18
16°FDec 3Dec 14Dec 24Jan 1Jan 4Jan 10Jan 16Jan 24Feb 5

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°F220212207202198193188182173
32°F246236231226221215211204197
28°F274263255249245240234228220
24°F307295288280273266259252243
20°F341329320311303297288278267
16°F365362351340333326317306294

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
97% of years
16°F or colder
83% 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
3,147
Cooling degree days, base 65°F
1,886
Growing degree days, base 40°F
8,134
Growing degree days, base 45°F
6,580
Growing degree days, base 50°F
5,173
Growing degree days, base 55°F
3,915
Growing degree days, base 60°F
2,819

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January732142
February560257
March40013170
April17653343
May45175595
June2357805
July0476941
August0454919
September13271708
October15374398
November4179137
December649258

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 12.8 km from Franklin 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 USC00017131 (Russellville #2). Public domain.