Pownal climate

Pownal Frost Dates and Growing Season

NOAA 1991-2020 normals for North Adams Harriman AP, 9.4 km from Pownal, elevation 654 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for North Adams Harriman AP. 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 May 10 and the first fall freeze around October 4, a growing season of about 147 days.

Median at 36°F
last May 22, first September 25
Median at 32°F
last May 10, first October 4
Median at 28°F
last April 30, first October 17

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°FJun 5May 31May 28May 25May 22May 19May 17May 13May 7
32°FMay 25May 20May 17May 14May 10May 7May 4Apr 30Apr 27
28°FMay 15May 9May 5May 2Apr 30Apr 27Apr 24Apr 20Apr 14
24°FMay 2Apr 25Apr 21Apr 18Apr 15Apr 11Apr 8Apr 4Mar 31
20°FApr 15Apr 9Apr 5Apr 3Apr 1Mar 30Mar 28Mar 23Mar 19
16°FApr 4Apr 1Mar 30Mar 27Mar 24Mar 21Mar 18Mar 15Mar 10

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 12Sep 16Sep 19Sep 22Sep 25Sep 28Oct 1Oct 3Oct 7
32°FSep 21Sep 27Sep 30Oct 1Oct 4Oct 6Oct 9Oct 14Oct 19
28°FOct 2Oct 6Oct 10Oct 13Oct 17Oct 20Oct 24Oct 30Nov 3
24°FOct 14Oct 20Oct 24Oct 28Oct 31Nov 3Nov 5Nov 10Nov 16
20°FOct 28Nov 1Nov 5Nov 8Nov 11Nov 15Nov 18Nov 22Nov 26
16°FNov 9Nov 14Nov 18Nov 22Nov 25Nov 27Dec 1Dec 5Dec 12

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°F142136131127124120116112104
32°F167159155150147143138133127
28°F193186180175170166161157149
24°F219211206201197192187181172
20°F245237232227223219214209203
16°F268260256252247243238233225

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
6,929
Cooling degree days, base 65°F
389
Growing degree days, base 40°F
4,291
Growing degree days, base 45°F
3,219
Growing degree days, base 50°F
2,291
Growing degree days, base 55°F
1,501
Growing degree days, base 60°F
861

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,29100
February1,10901
March97507
April596251
May28817220
June8071442
July16149598
August33112544
September17235320
October492290
November779016
December1,09902

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 9.4 km from Pownal. 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 USW00054768 (North Adams Harriman AP). Public domain.