Blackstone climate

Blackstone Frost Dates and Growing Season

NOAA 1991-2020 normals for Ft Pickett, 6.5 km from Blackstone, elevation 330 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Ft Pickett. 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 11 and the first fall freeze around October 30, a growing season of about 200 days.

Median at 36°F
last April 24, first October 21
Median at 32°F
last April 11, first October 30
Median at 28°F
last March 30, first November 7

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

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 8Oct 12Oct 15Oct 19Oct 21Oct 24Oct 26Oct 29Nov 1
32°FOct 16Oct 21Oct 24Oct 27Oct 30Nov 1Nov 3Nov 6Nov 11
28°FOct 26Oct 31Nov 1Nov 4Nov 7Nov 10Nov 14Nov 18Nov 27
24°FNov 3Nov 8Nov 12Nov 17Nov 21Nov 26Dec 1Dec 4Dec 12
20°FNov 12Nov 21Nov 28Dec 2Dec 5Dec 10Dec 18Dec 25Jan 2
16°FNov 30Dec 7Dec 15Dec 22Dec 28Jan 1Jan 8Jan 13Jan 21

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°F197191186183179176171166160
32°F220213208204200196192187180
28°F248238232227222218213209202
24°F277270263256250245239232223
20°F309298290284278273266258248
16°F338327319311306301294287276

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
99% 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
4,014
Cooling degree days, base 65°F
1,354
Growing degree days, base 40°F
6,898
Growing degree days, base 45°F
5,471
Growing degree days, base 50°F
4,210
Growing degree days, base 55°F
3,101
Growing degree days, base 60°F
2,151

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January857016
February699021
March559484
April27129243
May88105483
June10268708
July0395860
August1342806
September31176596
October23532281
November509284
December755128

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 6.5 km from Blackstone. 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 USC00441322 (Ft Pickett). Public domain.