Kittery climate

Kittery Frost Dates and Growing Season

NOAA 1991-2020 normals for Greenland, 10.4 km from Kittery, elevation 95 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Greenland. 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 4 and the first fall freeze around October 8, a growing season of about 157 days.

Median at 36°F
last May 16, first September 30
Median at 32°F
last May 4, first October 8
Median at 28°F
last April 23, first October 21

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 29May 25May 22May 19May 16May 13May 10May 7May 3
32°FMay 18May 14May 10May 7May 4May 2Apr 29Apr 27Apr 23
28°FMay 7May 2Apr 28Apr 25Apr 23Apr 20Apr 17Apr 12Apr 7
24°FApr 23Apr 18Apr 14Apr 10Apr 7Apr 5Apr 3Mar 31Mar 27
20°FApr 7Apr 3Apr 1Mar 30Mar 28Mar 24Mar 21Mar 17Mar 12
16°FMar 31Mar 27Mar 22Mar 19Mar 16Mar 14Mar 11Mar 8Mar 4

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 16Sep 21Sep 24Sep 27Sep 30Oct 2Oct 4Oct 6Oct 10
32°FSep 27Oct 1Oct 4Oct 6Oct 8Oct 11Oct 14Oct 18Oct 24
28°FOct 5Oct 10Oct 14Oct 18Oct 21Oct 24Oct 28Nov 1Nov 5
24°FOct 18Oct 25Oct 29Nov 1Nov 3Nov 6Nov 10Nov 13Nov 18
20°FNov 2Nov 7Nov 11Nov 14Nov 17Nov 20Nov 23Nov 28Dec 2
16°FNov 16Nov 21Nov 25Nov 29Dec 1Dec 3Dec 6Dec 10Dec 16

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°F154147142138134131126121115
32°F174168163160157153149144138
28°F201194189185180176171166158
24°F229221217212209205200195187
20°F255249243239234231226221214
16°F277270265261256253248243237

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
6,775
Cooling degree days, base 65°F
478
Growing degree days, base 40°F
4,390
Growing degree days, base 45°F
3,314
Growing degree days, base 50°F
2,385
Growing degree days, base 55°F
1,602
Growing degree days, base 60°F
961

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,25701
February1,07500
March95207
April593251
May31216196
June9379437
July14179629
August21148592
September14851357
October465398
November761016
December1,08301

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 10.4 km from Kittery. 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 USC00273626 (Greenland). Public domain.