Bernardston climate

Bernardston Frost Dates and Growing Season

NOAA 1991-2020 normals for Greenfield #3, 11.7 km from Bernardston, elevation 130 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Greenfield #3. 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 1 and the first fall freeze around October 11, a growing season of about 162 days.

Median at 36°F
last May 13, first October 1
Median at 32°F
last May 1, first October 11
Median at 28°F
last April 18, first October 25

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 28May 23May 19May 16May 13May 10May 7May 3Apr 30
32°FMay 15May 10May 6May 4May 1Apr 29Apr 26Apr 23Apr 19
28°FMay 4Apr 28Apr 23Apr 20Apr 18Apr 15Apr 12Apr 9Apr 6
24°FApr 18Apr 13Apr 10Apr 7Apr 4Apr 2Mar 31Mar 29Mar 22
20°FApr 6Apr 3Apr 1Mar 30Mar 27Mar 23Mar 20Mar 16Mar 12
16°FMar 31Mar 28Mar 24Mar 21Mar 18Mar 15Mar 12Mar 9Mar 5

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 19Sep 24Sep 27Sep 30Oct 1Oct 3Oct 6Oct 8Oct 14
32°FSep 29Oct 2Oct 5Oct 8Oct 11Oct 14Oct 17Oct 21Oct 28
28°FOct 8Oct 14Oct 17Oct 21Oct 25Oct 28Nov 1Nov 3Nov 7
24°FOct 21Oct 27Oct 31Nov 2Nov 4Nov 7Nov 11Nov 14Nov 18
20°FNov 2Nov 7Nov 11Nov 14Nov 17Nov 21Nov 24Nov 28Dec 2
16°FNov 13Nov 19Nov 23Nov 27Nov 30Dec 1Dec 4Dec 9Dec 15

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°F160154149146142139135130124
32°F183176171166162159155151144
28°F208202197193189185181175166
24°F234227222217213210206201195
20°F257250244240236232228223215
16°F277270264260256252248244237

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
6,683
Cooling degree days, base 65°F
519
Growing degree days, base 40°F
4,556
Growing degree days, base 45°F
3,473
Growing degree days, base 50°F
2,526
Growing degree days, base 55°F
1,710
Growing degree days, base 60°F
1,036

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,27200
February1,10600
March95207
April560257
May25721249
June6090481
July11196651
August21151595
September14055368
October4543104
November770014
December1,08201

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 11.7 km from Bernardston. 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 USC00193229 (Greenfield #3). Public domain.