Bridgewater climate

Bridgewater Frost Dates and Growing Season

NOAA 1991-2020 normals for Bridgewater, 0.1 km from Bridgewater, elevation 420 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Bridgewater. 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 25 and the first fall freeze around September 18, a growing season of about 115 days.

Median at 36°F
last June 8, first September 6
Median at 32°F
last May 25, first September 18
Median at 28°F
last May 9, first October 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°FJun 22Jun 16Jun 13Jun 11Jun 8Jun 5Jun 2May 30May 26
32°FJun 7Jun 3May 31May 28May 25May 22May 18May 14May 9
28°FMay 25May 20May 16May 12May 9May 6May 3Apr 30Apr 27
24°FMay 10May 5May 2Apr 30Apr 28Apr 25Apr 23Apr 20Apr 15
20°FApr 27Apr 23Apr 20Apr 18Apr 16Apr 14Apr 11Apr 8Apr 6
16°FApr 20Apr 16Apr 13Apr 10Apr 8Apr 7Apr 4Apr 2Mar 30

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°FAug 24Aug 29Sep 1Sep 4Sep 6Sep 9Sep 11Sep 15Sep 20
32°FSep 4Sep 8Sep 12Sep 16Sep 18Sep 21Sep 24Sep 27Oct 1
28°FSep 17Sep 22Sep 26Sep 28Oct 1Oct 3Oct 5Oct 9Oct 16
24°FOct 1Oct 4Oct 7Oct 10Oct 14Oct 17Oct 22Oct 26Nov 1
20°FOct 13Oct 19Oct 23Oct 27Oct 30Nov 1Nov 4Nov 8Nov 14
16°FOct 28Nov 1Nov 4Nov 7Nov 10Nov 14Nov 17Nov 20Nov 24

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°F10710096938985817668
32°F13512712211911511110710194
28°F162155151146142138134129121
24°F188182177172168163159155148
20°F213207203198194190187182174
16°F231226222219215211207203196

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
9,086
Cooling degree days, base 65°F
199
Growing degree days, base 40°F
3,357
Growing degree days, base 45°F
2,449
Growing degree days, base 50°F
1,669
Growing degree days, base 55°F
1,020
Growing degree days, base 60°F
522

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,65400
February1,42500
March1,23501
April79109
May4116124
June15533331
July4784502
August7760448
September27515216
October637035
November97403
December1,40600

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 0.1 km from Bridgewater. 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 USC00170833 (Bridgewater). Public domain.