Middleburg climate

Middleburg Frost Dates and Growing Season

NOAA 1991-2020 normals for Mt Wx, 16.9 km from Middleburg, elevation 1659 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Mt Wx. 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 17 and the first fall freeze around November 1, a growing season of about 198 days.

Median at 36°F
last April 29, first October 21
Median at 32°F
last April 17, first November 1
Median at 28°F
last April 6, first November 11

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 16May 9May 5May 1Apr 29Apr 25Apr 22Apr 19Apr 14
32°FMay 6Apr 30Apr 25Apr 21Apr 17Apr 14Apr 10Apr 7Apr 3
28°FApr 23Apr 17Apr 12Apr 9Apr 6Apr 4Apr 1Mar 30Mar 23
24°FApr 13Apr 7Apr 4Apr 1Mar 30Mar 26Mar 22Mar 18Mar 11
20°FApr 4Mar 31Mar 28Mar 23Mar 19Mar 16Mar 12Mar 7Feb 28
16°FMar 29Mar 22Mar 17Mar 13Mar 9Mar 5Mar 1Feb 24Feb 15

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 6Oct 11Oct 15Oct 19Oct 21Oct 24Oct 27Oct 30Nov 3
32°FOct 17Oct 23Oct 26Oct 30Nov 1Nov 3Nov 5Nov 9Nov 15
28°FOct 30Nov 2Nov 5Nov 8Nov 11Nov 13Nov 16Nov 20Nov 27
24°FNov 6Nov 11Nov 14Nov 18Nov 21Nov 24Nov 28Dec 2Dec 9
20°FNov 15Nov 21Nov 25Nov 29Dec 2Dec 6Dec 10Dec 16Dec 24
16°FNov 27Dec 2Dec 7Dec 12Dec 17Dec 22Dec 26Jan 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°F194186182178174169165159152
32°F217210205201198194189183173
28°F240232226222218214211206200
24°F264256249244239234229224217
20°F288278272265260255249243234
16°F310301294288283278273265257

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
5,302
Cooling degree days, base 65°F
848
Growing degree days, base 40°F
5,641
Growing degree days, base 45°F
4,379
Growing degree days, base 50°F
3,269
Growing degree days, base 55°F
2,313
Growing degree days, base 60°F
1,506

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,05404
February88506
March770136
April42014142
May18553342
June30169590
July3269732
August6232691
September7695472
October32915195
November619147
December927012

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 16.9 km from Middleburg. 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 USC00445851 (Mt Wx). Public domain.