Eastham climate

Eastham Frost Dates and Growing Season

NOAA 1991-2020 normals for Chatham, 19.3 km from Eastham, elevation 40 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Chatham. 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 5 and the first fall freeze around November 15, a growing season of about 221 days.

Median at 36°F
last April 19, first November 2
Median at 32°F
last April 5, first November 15
Median at 28°F
last March 28, first November 26

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 2Apr 27Apr 24Apr 22Apr 19Apr 17Apr 14Apr 11Apr 7
32°FApr 18Apr 12Apr 10Apr 7Apr 5Apr 3Apr 2Mar 31Mar 27
28°FApr 6Apr 4Apr 1Mar 31Mar 28Mar 25Mar 22Mar 19Mar 15
24°FMar 31Mar 27Mar 23Mar 20Mar 17Mar 15Mar 11Mar 8Mar 3
20°FMar 23Mar 18Mar 15Mar 11Mar 9Mar 6Mar 3Feb 28Feb 19
16°FMar 14Mar 8Mar 3Feb 28Feb 25Feb 22Feb 16Feb 9Feb 3

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 21Oct 27Oct 29Nov 1Nov 2Nov 5Nov 7Nov 10Nov 15
32°FNov 1Nov 5Nov 9Nov 12Nov 15Nov 17Nov 20Nov 24Nov 30
28°FNov 12Nov 17Nov 20Nov 23Nov 26Nov 30Dec 2Dec 5Dec 12
24°FNov 24Nov 28Dec 1Dec 4Dec 7Dec 11Dec 16Dec 21Dec 28
20°FDec 3Dec 8Dec 14Dec 17Dec 21Dec 25Dec 29Jan 3Jan 10
16°FDec 15Dec 21Dec 26Dec 30Jan 2Jan 5Jan 10Jan 15Jan 21

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°F212207203199195192189184178
32°F241233229225221217214211205
28°F265258253248244240236232226
24°F287279274270266261257252245
20°F306300295290286282277271263
16°F329321317310306302297292285

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
5,681
Cooling degree days, base 65°F
369
Growing degree days, base 40°F
4,613
Growing degree days, base 45°F
3,399
Growing degree days, base 50°F
2,378
Growing degree days, base 55°F
1,543
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
January1,03100
February92500
March87101
April591014
May3451139
June9933384
July8147605
August6140600
September6646431
October3152175
November576029
December84902

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 19.3 km from Eastham. Low ground, valleys and open fields freeze earlier and later than a town center or a hillside.

More

Sources

NOAA NCEI U.S. Climate Normals, 1991-2020, annual and seasonal normals for station USC00191386 (Chatham). Public domain.