Crozet climate

Crozet Frost Dates and Growing Season

NOAA 1991-2020 normals for Free Union, 10 km from Crozet, elevation 590 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Free Union. 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 24, a growing season of about 186 days.

Median at 36°F
last April 30, first October 14
Median at 32°F
last April 19, first October 24
Median at 28°F
last April 7, 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 11May 6May 3Apr 30Apr 27Apr 24Apr 20Apr 17
32°FMay 5Apr 30Apr 25Apr 22Apr 19Apr 17Apr 14Apr 10Apr 5
28°FApr 21Apr 15Apr 12Apr 9Apr 7Apr 5Apr 2Mar 30Mar 25
24°FApr 9Apr 5Apr 2Mar 31Mar 28Mar 25Mar 21Mar 17Mar 11
20°FMar 31Mar 27Mar 23Mar 19Mar 16Mar 12Mar 8Mar 3Feb 26
16°FMar 22Mar 16Mar 12Mar 8Mar 4Feb 28Feb 25Feb 17Feb 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 3Oct 6Oct 9Oct 12Oct 14Oct 17Oct 20Oct 23Oct 29
32°FOct 10Oct 14Oct 18Oct 21Oct 24Oct 27Oct 29Nov 1Nov 5
28°FOct 19Oct 25Oct 28Oct 30Nov 1Nov 4Nov 7Nov 10Nov 14
24°FOct 30Nov 2Nov 5Nov 8Nov 12Nov 15Nov 18Nov 23Nov 30
20°FNov 9Nov 15Nov 19Nov 22Nov 27Dec 1Dec 3Dec 8Dec 16
16°FNov 21Nov 29Dec 3Dec 8Dec 13Dec 20Dec 24Dec 30Jan 6

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°F186179175171167164159154147
32°F206199194190186182177172165
28°F226220215211207203199194187
24°F254246239233230225221216209
20°F282272266261256251246239230
16°F313304296290285279274268257

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
4,642
Cooling degree days, base 65°F
948
Growing degree days, base 40°F
6,053
Growing degree days, base 45°F
4,714
Growing degree days, base 50°F
3,538
Growing degree days, base 55°F
2,512
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
January94506
February788011
March656152
April32613187
May13156393
June14182618
July1307772
August3259721
September61112501
October29519218
November575050
December848010

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 10 km from Crozet. 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 USC00443213 (Free Union). Public domain.