Cullowhee climate

Cullowhee Frost Dates and Growing Season

NOAA 1991-2020 normals for Cullowhee, 0.3 km from Cullowhee, elevation 2192 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Cullowhee. 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 19 and the first fall freeze around October 22, a growing season of about 184 days.

Median at 36°F
last May 3, first October 13
Median at 32°F
last April 19, first October 22
Median at 28°F
last April 5, first November 1

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 17May 12May 9May 6May 3Apr 30Apr 27Apr 22Apr 17
32°FMay 7May 1Apr 26Apr 22Apr 19Apr 16Apr 13Apr 9Apr 2
28°FApr 21Apr 15Apr 12Apr 8Apr 5Apr 1Mar 30Mar 26Mar 20
24°FApr 7Apr 2Mar 31Mar 27Mar 24Mar 20Mar 16Mar 10Mar 2
20°FMar 28Mar 23Mar 17Mar 13Mar 9Mar 5Feb 28Feb 22Feb 12
16°FMar 20Mar 12Mar 5Feb 28Feb 22Feb 16Feb 8Feb 1Jan 24

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 1Oct 5Oct 8Oct 11Oct 13Oct 16Oct 18Oct 22Oct 27
32°FOct 9Oct 13Oct 16Oct 19Oct 22Oct 25Oct 29Nov 1Nov 4
28°FOct 17Oct 22Oct 25Oct 29Nov 1Nov 2Nov 5Nov 8Nov 12
24°FOct 29Nov 1Nov 4Nov 7Nov 10Nov 13Nov 16Nov 21Nov 29
20°FNov 7Nov 12Nov 16Nov 20Nov 24Nov 28Dec 2Dec 8Dec 22
16°FNov 19Nov 26Dec 1Dec 6Dec 12Dec 19Dec 27Jan 1Jan 9

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°F183176171167163159155150144
32°F207198193188184179176171164
28°F231222217212207203198192186
24°F259250243238233228223217210
20°F295282274268263257251245234
16°F330319309302294286280271261

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
4,130
Cooling degree days, base 65°F
901
Growing degree days, base 40°F
6,332
Growing degree days, base 45°F
4,901
Growing degree days, base 50°F
3,646
Growing degree days, base 55°F
2,566
Growing degree days, base 60°F
1,651

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January866010
February686016
March546172
April28210212
May9960429
June12177615
July0279744
August1249713
September38112524
October26413240
November557054
December778018

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 0.3 km from Cullowhee. 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 USC00312200 (Cullowhee). Public domain.