Franklin climate

Franklin Frost Dates and Growing Season

NOAA 1991-2020 normals for Franklin #2, 0.7 km from Franklin, elevation 1861 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Franklin #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 April 30 and the first fall freeze around October 8, a growing season of about 161 days.

Median at 36°F
last May 7, first October 1
Median at 32°F
last April 30, first October 8
Median at 28°F
last April 19, first October 19

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 21May 16May 12May 9May 7May 5May 2Apr 30Apr 25
32°FMay 12May 7May 4May 2Apr 30Apr 27Apr 24Apr 20Apr 16
28°FMay 3Apr 29Apr 25Apr 22Apr 19Apr 17Apr 14Apr 9Apr 5
24°FApr 25Apr 20Apr 17Apr 13Apr 9Apr 5Apr 2Mar 30Mar 23
20°FApr 17Apr 9Apr 5Apr 2Mar 30Mar 26Mar 21Mar 16Mar 11
16°FApr 6Mar 31Mar 28Mar 22Mar 18Mar 14Mar 10Mar 6Mar 2

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 18Sep 23Sep 26Sep 29Oct 1Oct 3Oct 5Oct 9Oct 13
32°FSep 25Sep 30Oct 3Oct 5Oct 8Oct 12Oct 14Oct 17Oct 21
28°FOct 1Oct 8Oct 13Oct 16Oct 19Oct 21Oct 23Oct 26Oct 31
24°FOct 14Oct 19Oct 22Oct 25Oct 28Oct 31Nov 1Nov 5Nov 10
20°FOct 21Oct 27Oct 31Nov 2Nov 5Nov 8Nov 11Nov 15Nov 20
16°FOct 29Nov 3Nov 7Nov 10Nov 13Nov 16Nov 20Nov 24Nov 30

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°F160155151148144141137132125
32°F180173169165161158154149142
28°F200194189185181176172167160
24°F222213209205201197192186180
20°F243236229224219214210205198
16°F263256248243238232227221212

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
6,065
Cooling degree days, base 65°F
1,071
Growing degree days, base 40°F
5,591
Growing degree days, base 45°F
4,423
Growing degree days, base 50°F
3,389
Growing degree days, base 55°F
2,485
Growing degree days, base 60°F
1,714

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,20600
February99004
March771134
April4596118
May19356345
June23220647
July2363826
August7292750
September98121477
October40513165
November782023
December1,13001

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 0.7 km from Franklin. 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 USC00253037 (Franklin #2). Public domain.