Franklin County climate

Franklin County Frost Dates and Growing Season

NOAA 1991-2020 normals for Louisburg, 2.7 km from Franklin County, elevation 260 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Louisburg. 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 11 and the first fall freeze around October 29, a growing season of about 201 days.

Median at 36°F
last April 22, first October 20
Median at 32°F
last April 11, first October 29
Median at 28°F
last March 29, first November 6

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 10May 4Apr 30Apr 26Apr 22Apr 19Apr 17Apr 14Apr 8
32°FApr 28Apr 20Apr 17Apr 14Apr 11Apr 8Apr 4Mar 31Mar 25
28°FApr 12Apr 7Apr 4Apr 1Mar 29Mar 26Mar 23Mar 18Mar 11
24°FApr 3Mar 29Mar 24Mar 20Mar 16Mar 11Mar 7Feb 28Feb 22
20°FMar 23Mar 16Mar 10Mar 6Feb 28Feb 24Feb 18Feb 10Feb 2
16°FMar 11Mar 4Feb 25Feb 17Feb 9Feb 4Jan 31Jan 23Jan 14

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 6Oct 11Oct 14Oct 17Oct 20Oct 22Oct 25Oct 29Nov 1
32°FOct 15Oct 20Oct 23Oct 26Oct 29Nov 1Nov 3Nov 6Nov 11
28°FOct 24Oct 30Nov 1Nov 4Nov 6Nov 9Nov 13Nov 18Nov 25
24°FNov 5Nov 9Nov 12Nov 17Nov 20Nov 25Nov 30Dec 4Dec 12
20°FNov 14Nov 21Nov 28Dec 2Dec 7Dec 12Dec 20Dec 30Jan 7
16°FNov 29Dec 7Dec 15Dec 24Jan 1Jan 3Jan 11Jan 16Jan 26

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°F200193188184180176172166159
32°F221214209205201197193188180
28°F248239232228223219215210202
24°F280269262255249244238232224
20°F315304297288282274266258249
16°F353337330323315307302294282

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
96% 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
3,647
Cooling degree days, base 65°F
1,545
Growing degree days, base 40°F
7,336
Growing degree days, base 45°F
5,854
Growing degree days, base 50°F
4,534
Growing degree days, base 55°F
3,376
Growing degree days, base 60°F
2,383

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January789024
February638133
March4986106
April23635272
May72125518
June7304747
July0439904
August1383848
September22209637
October20740313
November479294
December697139

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 2.7 km from Franklin 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 USC00315123 (Louisburg). Public domain.