Seneca climate

Seneca Frost Dates and Growing Season

NOAA 1991-2020 normals for Clemson Oconee CO AP, 6.3 km from Seneca, elevation 891 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Clemson Oconee CO AP. 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 21 and the first fall freeze around November 11, a growing season of about 236 days.

Median at 36°F
last April 3, first November 1
Median at 32°F
last March 21, first November 11
Median at 28°F
last March 7, first November 27

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 19Apr 14Apr 10Apr 6Apr 3Apr 1Mar 28Mar 24Mar 18
32°FApr 7Apr 1Mar 28Mar 25Mar 21Mar 18Mar 14Mar 8Mar 1
28°FMar 24Mar 18Mar 15Mar 11Mar 7Mar 2Feb 26Feb 20Feb 10
24°FMar 15Mar 7Mar 1Feb 24Feb 19Feb 13Feb 5Jan 30Jan 19
20°FMar 4Feb 22Feb 13Feb 6Jan 31Jan 27Jan 21Jan 14Jan 4
16°FFeb 18Feb 7Feb 1Jan 29Jan 24Jan 18Jan 14Jan 7Dec 31

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 19Oct 24Oct 27Oct 30Nov 1Nov 4Nov 6Nov 10Nov 15
32°FOct 28Nov 2Nov 5Nov 8Nov 11Nov 15Nov 19Nov 24Dec 1
28°FNov 8Nov 13Nov 18Nov 22Nov 27Dec 1Dec 5Dec 10Dec 21
24°FNov 21Nov 29Dec 4Dec 8Dec 14Dec 23Dec 29Jan 3Jan 13
20°FDec 7Dec 15Dec 24Dec 29Jan 2Jan 7Jan 13Jan 19Jan 30
16°FDec 21Dec 30Jan 2Jan 6Jan 12Jan 16Jan 20Jan 28Feb 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°F233226221216212208203198192
32°F263254246241236231226221212
28°F298285277271266260254246238
24°F332322314307300293285278265
20°F365353344336331324316306293
16°F365365365365355346338331319

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
88% of years
16°F or colder
59% 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
2,960
Cooling degree days, base 65°F
1,666
Growing degree days, base 40°F
7,979
Growing degree days, base 45°F
6,380
Growing degree days, base 50°F
4,946
Growing degree days, base 55°F
3,677
Growing degree days, base 60°F
2,583

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January690032
February533149
March3748164
April16037335
May38154581
June2321770
July0443908
August0405870
September10243682
October14049379
November3924127
December621148

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 6.3 km from Seneca. 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 USW00053850 (Clemson Oconee CO AP). Public domain.