New England climate

New England Frost Dates and Growing Season

NOAA 1991-2020 normals for New England, 0.2 km from New England, elevation 2600 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for New England. 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 16 and the first fall freeze around September 24, a growing season of about 128 days.

Median at 36°F
last May 27, first September 15
Median at 32°F
last May 16, first September 24
Median at 28°F
last May 7, first October 2

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 10Jun 5Jun 2May 30May 27May 25May 23May 19May 15
32°FMay 29May 26May 22May 19May 16May 14May 12May 9May 6
28°FMay 20May 15May 11May 9May 7May 4May 2Apr 30Apr 24
24°FMay 10May 6May 3Apr 30Apr 28Apr 25Apr 21Apr 17Apr 12
20°FMay 1Apr 26Apr 23Apr 20Apr 17Apr 14Apr 12Apr 9Apr 5
16°FApr 24Apr 18Apr 15Apr 12Apr 9Apr 7Apr 4Apr 1Mar 25

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 2Sep 5Sep 9Sep 12Sep 15Sep 17Sep 20Sep 23Sep 27
32°FSep 10Sep 15Sep 18Sep 21Sep 24Sep 26Sep 29Oct 2Oct 5
28°FSep 17Sep 23Sep 27Sep 30Oct 2Oct 4Oct 6Oct 10Oct 15
24°FSep 26Oct 2Oct 5Oct 8Oct 10Oct 14Oct 17Oct 20Oct 24
20°FOct 6Oct 10Oct 14Oct 17Oct 19Oct 22Oct 25Oct 28Nov 1
16°FOct 13Oct 18Oct 22Oct 25Oct 28Oct 31Nov 2Nov 6Nov 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°F1281221171131101061029791
32°F145139135132128124120116110
28°F163158154150146142138134127
24°F182176171167163160156151145
20°F202195190186182178173169163
16°F223213209205200196191186179

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
8,317
Cooling degree days, base 65°F
438
Growing degree days, base 40°F
3,975
Growing degree days, base 45°F
3,006
Growing degree days, base 50°F
2,164
Growing degree days, base 55°F
1,451
Growing degree days, base 60°F
870

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,49700
February1,25400
March1,05704
April683031
May3559177
June10557404
July24178618
August39157583
September21835290
October646153
November1,03803
December1,40000

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 0.2 km from New England. 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 USC00326315 (New England). Public domain.