Fairfield Harbour climate

Fairfield Harbour Frost Dates and Growing Season

NOAA 1991-2020 normals for Reelsboro, 7.5 km from Fairfield Harbour, elevation 45 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Reelsboro. 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 March 21 and the first fall freeze around November 17, a growing season of about 242 days.

Median at 36°F
last April 3, first November 4
Median at 32°F
last March 21, first November 17
Median at 28°F
last March 8, first December 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°FApr 18Apr 12Apr 8Apr 5Apr 3Mar 31Mar 28Mar 25Mar 19
32°FApr 5Mar 31Mar 28Mar 25Mar 21Mar 18Mar 15Mar 11Mar 4
28°FMar 27Mar 21Mar 16Mar 12Mar 8Mar 4Feb 28Feb 22Feb 12
24°FMar 15Mar 6Mar 1Feb 24Feb 16Feb 8Feb 1Jan 25Jan 11
20°FFeb 28Feb 19Feb 6Jan 31Jan 27Jan 21Jan 14Jan 7Dec 30
16°FFeb 10Feb 1Jan 27Jan 22Jan 16Jan 13Jan 9Jan 3Dec 27

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 23Oct 28Oct 31Nov 2Nov 4Nov 7Nov 10Nov 14Nov 19
32°FNov 1Nov 5Nov 10Nov 13Nov 17Nov 20Nov 25Dec 1Dec 6
28°FNov 12Nov 19Nov 23Nov 28Dec 1Dec 4Dec 10Dec 21Jan 1
24°FNov 26Dec 3Dec 9Dec 16Dec 23Dec 30Jan 5Jan 11Jan 20
20°FDec 8Dec 20Dec 28Jan 1Jan 7Jan 13Jan 18Jan 26Feb 8
16°FDec 23Dec 30Jan 3Jan 9Jan 13Jan 16Jan 21Jan 28Feb 3

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°F238230225221216213209204197
32°F268258252247242237233227220
28°F304294285280273267261254245
24°F344334323316309302294285274
20°F365365361352341334327316304
16°F365365365365365365362347333

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
98% of years
20°F or colder
75% of years
16°F or colder
35% 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
2,494
Cooling degree days, base 65°F
1,918
Growing degree days, base 40°F
8,650
Growing degree days, base 45°F
6,987
Growing degree days, base 50°F
5,468
Growing degree days, base 55°F
4,111
Growing degree days, base 60°F
2,929

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January586271
February469488
March35315183
April12764393
May24184625
June1361810
July0483948
August0429894
September5281726
October10482446
November31910182
December5074102

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 7.5 km from Fairfield Harbour. 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 USC00317170 (Reelsboro). Public domain.