Sullivan County climate

Sullivan County Frost Dates and Growing Season

NOAA 1991-2020 normals for Green City 5N, 20.7 km from Sullivan County, elevation 1035 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Green City 5N. 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 26 and the first fall freeze around October 14, a growing season of about 169 days.

Median at 36°F
last May 5, first October 3
Median at 32°F
last April 26, first October 14
Median at 28°F
last April 14, first October 24

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 15May 12May 8May 5May 2Apr 29Apr 26Apr 19
32°FMay 12May 5May 2Apr 30Apr 26Apr 23Apr 19Apr 15Apr 11
28°FApr 30Apr 25Apr 21Apr 17Apr 14Apr 11Apr 9Apr 5Apr 1
24°FApr 20Apr 14Apr 11Apr 8Apr 5Apr 2Mar 31Mar 26Mar 19
20°FApr 11Apr 6Apr 2Mar 31Mar 27Mar 22Mar 18Mar 13Mar 8
16°FApr 2Mar 28Mar 23Mar 19Mar 15Mar 12Mar 8Mar 6Mar 1

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 20Sep 25Sep 28Oct 1Oct 3Oct 6Oct 9Oct 12Oct 17
32°FSep 30Oct 4Oct 8Oct 11Oct 14Oct 16Oct 19Oct 22Oct 27
28°FOct 9Oct 15Oct 18Oct 22Oct 24Oct 26Oct 29Nov 1Nov 5
24°FOct 21Oct 24Oct 28Oct 30Nov 1Nov 3Nov 6Nov 10Nov 16
20°FOct 30Nov 1Nov 5Nov 7Nov 11Nov 13Nov 17Nov 22Nov 28
16°FNov 5Nov 10Nov 13Nov 16Nov 20Nov 23Nov 28Dec 1Dec 7

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°F169162157153149145141135129
32°F187182177173169165160156149
28°F210202198193189186182177169
24°F232222217212209206201197190
20°F254244237234229224219214206
16°F271263258252248244239234227

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
6,341
Cooling degree days, base 65°F
846
Growing degree days, base 40°F
5,315
Growing degree days, base 45°F
4,162
Growing degree days, base 50°F
3,140
Growing degree days, base 55°F
2,248
Growing degree days, base 60°F
1,479

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,31900
February1,06104
March812237
April4566124
May19748334
June22171598
July5286745
August10230685
September11091435
October41713155
November780023
December1,15201

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 20.7 km from Sullivan 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 USC00233416 (Green City 5N). Public domain.