Butner climate

Butner Frost Dates and Growing Season

NOAA 1991-2020 normals for Falls Lake, 19.2 km from Butner, elevation 280 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Falls Lake. 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 4 and the first fall freeze around November 4, a growing season of about 213 days.

Median at 36°F
last April 17, first October 26
Median at 32°F
last April 4, first November 4
Median at 28°F
last March 24, first November 15

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 2Apr 27Apr 23Apr 20Apr 17Apr 14Apr 11Apr 8Apr 2
32°FApr 19Apr 13Apr 10Apr 7Apr 4Apr 1Mar 30Mar 25Mar 20
28°FApr 9Apr 3Mar 31Mar 28Mar 24Mar 20Mar 17Mar 13Mar 7
24°FMar 29Mar 21Mar 17Mar 14Mar 11Mar 6Mar 2Feb 26Feb 16
20°FMar 16Mar 9Mar 5Mar 1Feb 25Feb 17Feb 9Feb 2Jan 25
16°FMar 5Feb 27Feb 16Feb 7Feb 2Jan 29Jan 24Jan 16Jan 7

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 14Oct 17Oct 21Oct 23Oct 26Oct 29Oct 31Nov 2Nov 6
32°FOct 22Oct 27Oct 30Nov 1Nov 4Nov 6Nov 9Nov 12Nov 18
28°FNov 1Nov 5Nov 8Nov 11Nov 15Nov 17Nov 21Nov 26Dec 1
24°FNov 11Nov 17Nov 21Nov 26Dec 1Dec 4Dec 8Dec 16Dec 29
20°FNov 30Dec 5Dec 10Dec 18Dec 24Dec 31Jan 3Jan 9Jan 17
16°FDec 13Dec 24Dec 30Jan 2Jan 7Jan 12Jan 17Jan 23Feb 1

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°F210204198195191187182178171
32°F233225221217213209205200195
28°F263253246241237232227223216
24°F299288281274268262255249242
20°F335324315307301295290282273
16°F365356347337332326317308297

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
99% of years
16°F or colder
88% 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
3,819
Cooling degree days, base 65°F
1,324
Growing degree days, base 40°F
6,978
Growing degree days, base 45°F
5,523
Growing degree days, base 50°F
4,233
Growing degree days, base 55°F
3,104
Growing degree days, base 60°F
2,134

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January818020
February658030
March5105103
April24133268
May79101488
June5266711
July0392857
August0332797
September27169592
October24624263
November511173
December723031

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 19.2 km from Butner. 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 USC00312993 (Falls Lake). Public domain.