Danville climate

Danville Frost Dates and Growing Season

NOAA 1991-2020 normals for Burlington 2S, 19.5 km from Danville, elevation 690 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Burlington 2S. 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 18 and the first fall freeze around October 20, a growing season of about 185 days.

Median at 36°F
last April 30, first October 11
Median at 32°F
last April 18, first October 20
Median at 28°F
last April 7, first October 31

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 12May 8May 5May 2Apr 30Apr 26Apr 23Apr 19Apr 14
32°FMay 3Apr 29Apr 24Apr 21Apr 18Apr 14Apr 11Apr 8Apr 3
28°FApr 23Apr 18Apr 13Apr 10Apr 7Apr 4Apr 2Mar 30Mar 23
24°FApr 13Apr 8Apr 4Apr 1Mar 30Mar 26Mar 22Mar 18Mar 11
20°FApr 3Mar 30Mar 26Mar 22Mar 18Mar 15Mar 11Mar 8Mar 4
16°FMar 27Mar 21Mar 17Mar 14Mar 10Mar 8Mar 5Mar 2Feb 25

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 26Oct 1Oct 5Oct 8Oct 11Oct 13Oct 16Oct 19Oct 23
32°FOct 6Oct 12Oct 15Oct 18Oct 20Oct 23Oct 25Oct 29Nov 2
28°FOct 17Oct 22Oct 26Oct 29Oct 31Nov 1Nov 4Nov 8Nov 12
24°FOct 28Nov 1Nov 3Nov 5Nov 8Nov 11Nov 14Nov 18Nov 23
20°FNov 5Nov 8Nov 12Nov 15Nov 18Nov 22Nov 25Nov 29Dec 4
16°FNov 9Nov 15Nov 19Nov 23Nov 26Nov 29Dec 2Dec 7Dec 13

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°F182176170166163160156150142
32°F203197192188185181175170163
28°F225218213209205201196191184
24°F247240234229225220217212204
20°F267259253248243239234228222
16°F284275270264259254249245237

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
6,006
Cooling degree days, base 65°F
1,023
Growing degree days, base 40°F
5,682
Growing degree days, base 45°F
4,502
Growing degree days, base 50°F
3,445
Growing degree days, base 55°F
2,511
Growing degree days, base 60°F
1,700

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,28600
February1,03303
March785238
April4179139
May15268388
June17219652
July2321784
August5267727
September84119487
October36117191
November742133
December1,12202

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 19.5 km from Danville. 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 USC00131060 (Burlington 2S). Public domain.