Bristol climate

Bristol Frost Dates and Growing Season

NOAA 1991-2020 normals for Goshen 3SW, 19 km from Bristol, elevation 875 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Goshen 3SW. 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 26 and the first fall freeze around October 21, a growing season of about 175 days.

Median at 36°F
last May 6, first October 7
Median at 32°F
last April 26, first October 21
Median at 28°F
last April 16, first November 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°FMay 21May 16May 12May 9May 6May 3Apr 30Apr 27Apr 23
32°FMay 12May 7May 3Apr 30Apr 26Apr 23Apr 20Apr 17Apr 13
28°FMay 1Apr 25Apr 21Apr 18Apr 16Apr 12Apr 8Apr 5Apr 1
24°FApr 19Apr 13Apr 9Apr 6Apr 3Apr 1Mar 30Mar 26Mar 19
20°FApr 6Apr 2Mar 31Mar 27Mar 24Mar 21Mar 17Mar 13Mar 7
16°FMar 30Mar 25Mar 20Mar 17Mar 14Mar 10Mar 7Mar 3Feb 24

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 26Sep 30Oct 3Oct 5Oct 7Oct 10Oct 13Oct 16Oct 21
32°FOct 6Oct 11Oct 15Oct 18Oct 21Oct 23Oct 26Oct 29Nov 2
28°FOct 19Oct 23Oct 27Oct 30Nov 1Nov 3Nov 6Nov 10Nov 14
24°FNov 1Nov 4Nov 7Nov 10Nov 12Nov 15Nov 18Nov 23Nov 28
20°FNov 8Nov 13Nov 17Nov 20Nov 23Nov 27Nov 30Dec 4Dec 9
16°FNov 15Nov 21Nov 26Nov 29Dec 2Dec 5Dec 10Dec 16Dec 22

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°F172166161157153149144139132
32°F195189183179175171167161153
28°F220212207203199195190184177
24°F244236231226222218214210203
20°F268260254249244240235230224
16°F288280274268264259254249241

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
6,116
Cooling degree days, base 65°F
793
Growing degree days, base 40°F
5,279
Growing degree days, base 45°F
4,120
Growing degree days, base 50°F
3,093
Growing degree days, base 55°F
2,193
Growing degree days, base 60°F
1,423

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,24801
February1,04002
March838127
April4705108
May18757347
June26176600
July4254715
August10205660
September9783439
October38110164
November732029
December1,08203

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 19 km from Bristol. 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 USC00123418 (Goshen 3SW). Public domain.