Warren County climate

Warren County Frost Dates and Growing Season

NOAA 1991-2020 normals for Franklin, 19.1 km from Warren County, elevation 679 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Franklin. 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 24 and the first fall freeze around October 19, a growing season of about 178 days.

Median at 36°F
last May 4, first October 9
Median at 32°F
last April 24, first October 19
Median at 28°F
last April 11, first October 29

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 19May 14May 10May 7May 4May 1Apr 28Apr 24Apr 20
32°FMay 11May 5May 1Apr 28Apr 24Apr 21Apr 18Apr 14Apr 9
28°FApr 30Apr 22Apr 18Apr 15Apr 11Apr 7Apr 4Apr 1Mar 26
24°FApr 15Apr 8Apr 4Apr 1Mar 30Mar 26Mar 23Mar 19Mar 10
20°FApr 2Mar 30Mar 26Mar 22Mar 19Mar 15Mar 11Mar 6Feb 28
16°FMar 24Mar 18Mar 14Mar 10Mar 6Mar 2Feb 27Feb 22Feb 13

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 27Oct 1Oct 4Oct 6Oct 9Oct 11Oct 13Oct 16Oct 21
32°FOct 7Oct 11Oct 13Oct 16Oct 19Oct 21Oct 24Oct 27Nov 1
28°FOct 16Oct 20Oct 23Oct 26Oct 29Oct 31Nov 2Nov 5Nov 11
24°FOct 25Oct 30Nov 1Nov 4Nov 7Nov 10Nov 13Nov 17Nov 25
20°FNov 3Nov 8Nov 12Nov 15Nov 19Nov 24Nov 29Dec 3Dec 11
16°FNov 14Nov 21Nov 27Dec 1Dec 4Dec 7Dec 13Dec 22Dec 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°F177171165161158154149144137
32°F197191186182178173169163157
28°F219212207204199195191186178
24°F249240232227222218213208202
20°F274266260254248242237231223
16°F302293285280273268262254246

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
5,409
Cooling degree days, base 65°F
956
Growing degree days, base 40°F
5,741
Growing degree days, base 45°F
4,502
Growing degree days, base 50°F
3,407
Growing degree days, base 55°F
2,450
Growing degree days, base 60°F
1,632

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,10404
February92704
March742141
April3999148
May15068390
June19203634
July2301764
August4255716
September77107481
October35512176
November671039
December96109

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 19.1 km from Warren 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 USC00332928 (Franklin). Public domain.