Mitchell County climate

Mitchell County Frost Dates and Growing Season

NOAA 1991-2020 normals for Burnsville Ag, 13.8 km from Mitchell County, elevation 2825 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Burnsville Ag. 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 24 and the first fall freeze around October 19, a growing season of about 180 days.

Median at 36°F
last May 6, first October 10
Median at 32°F
last April 24, first October 19
Median at 28°F
last April 6, first October 28

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 22May 16May 12May 9May 6May 3Apr 30Apr 25Apr 18
32°FMay 13May 7May 2Apr 28Apr 24Apr 20Apr 15Apr 11Apr 5
28°FMay 1Apr 21Apr 15Apr 10Apr 6Apr 4Mar 31Mar 27Mar 21
24°FApr 8Apr 4Mar 31Mar 28Mar 25Mar 20Mar 17Mar 13Mar 7
20°FMar 30Mar 24Mar 19Mar 15Mar 12Mar 7Mar 3Feb 27Feb 19
16°FMar 20Mar 13Mar 7Mar 1Feb 25Feb 19Feb 11Feb 4Jan 28

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 29Oct 3Oct 6Oct 8Oct 10Oct 13Oct 16Oct 20Oct 26
32°FOct 7Oct 10Oct 13Oct 16Oct 19Oct 22Oct 26Oct 30Nov 3
28°FOct 13Oct 17Oct 21Oct 25Oct 28Nov 1Nov 3Nov 7Nov 13
24°FOct 21Oct 27Oct 31Nov 3Nov 7Nov 11Nov 15Nov 20Nov 27
20°FNov 1Nov 7Nov 14Nov 18Nov 22Nov 27Dec 1Dec 6Dec 15
16°FNov 15Nov 24Dec 1Dec 5Dec 8Dec 13Dec 20Dec 27Jan 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°F179172166161157153149143136
32°F202194189185180175170163154
28°F226219212208203199193187178
24°F253245238232228223217212203
20°F287275269262256250244236229
16°F324312304296289282274265253

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
4,576
Cooling degree days, base 65°F
635
Growing degree days, base 40°F
5,751
Growing degree days, base 45°F
4,368
Growing degree days, base 50°F
3,168
Growing degree days, base 55°F
2,151
Growing degree days, base 60°F
1,301

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January91408
February725016
March614057
April3353167
May15124347
June15135570
July3226688
August4172632
September7269448
October3326182
November587043
December825012

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 13.8 km from Mitchell 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 USC00311248 (Burnsville Ag). Public domain.