Graham County climate

Graham County Frost Dates and Growing Season

NOAA 1991-2020 normals for Robbinsville Ag 5 Ne, 12.5 km from Graham County, elevation 2330 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Robbinsville Ag 5 Ne. 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 13 and the first fall freeze around October 26, a growing season of about 194 days.

Median at 36°F
last April 28, first October 17
Median at 32°F
last April 13, first October 26
Median at 28°F
last March 31, first November 3

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 13May 9May 4May 1Apr 28Apr 24Apr 20Apr 16Apr 12
32°FMay 2Apr 25Apr 20Apr 17Apr 13Apr 11Apr 7Apr 4Mar 30
28°FApr 18Apr 11Apr 6Apr 3Mar 31Mar 29Mar 25Mar 20Mar 15
24°FApr 5Mar 31Mar 28Mar 24Mar 20Mar 16Mar 12Mar 7Mar 1
20°FMar 27Mar 21Mar 15Mar 10Mar 6Mar 3Feb 28Feb 20Feb 11
16°FMar 15Mar 6Mar 2Feb 25Feb 19Feb 13Feb 6Jan 31Jan 23

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 5Oct 9Oct 12Oct 15Oct 17Oct 19Oct 22Oct 25Oct 29
32°FOct 12Oct 17Oct 20Oct 23Oct 26Oct 28Oct 31Nov 1Nov 6
28°FOct 21Oct 26Oct 30Nov 1Nov 3Nov 6Nov 9Nov 13Nov 19
24°FNov 2Nov 6Nov 10Nov 13Nov 16Nov 20Nov 23Nov 28Dec 4
20°FNov 12Nov 17Nov 23Nov 27Dec 1Dec 3Dec 7Dec 16Dec 25
16°FNov 27Dec 1Dec 5Dec 11Dec 19Dec 25Dec 30Jan 3Jan 12

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°F190184179175171167163158151
32°F214207202198194189185179171
28°F239231226221217212208202194
24°F267259252247242238232227220
20°F300289281275270264257251242
16°F335323315307301294288278268

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
99% 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
4,367
Cooling degree days, base 65°F
763
Growing degree days, base 40°F
6,112
Growing degree days, base 45°F
4,708
Growing degree days, base 50°F
3,463
Growing degree days, base 55°F
2,400
Growing degree days, base 60°F
1,501

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January91909
February725018
March585168
April29913211
May11954405
June15133569
July2241704
August2212674
September4798501
October27613233
November560055
December818017

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 12.5 km from Graham 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 USC00317344 (Robbinsville Ag 5 Ne). Public domain.