West Wareham climate

West Wareham Frost Dates and Growing Season

NOAA 1991-2020 normals for E Wareham, 8 km from West Wareham, elevation 30 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for E Wareham. 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 21 and the first fall freeze around October 24, a growing season of about 186 days.

Median at 36°F
last May 2, first October 14
Median at 32°F
last April 21, first October 24
Median at 28°F
last April 6, first November 4

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 14May 9May 6May 4May 2Apr 30Apr 28Apr 25Apr 22
32°FMay 3Apr 30Apr 26Apr 24Apr 21Apr 19Apr 16Apr 12Apr 7
28°FApr 21Apr 16Apr 13Apr 10Apr 6Apr 4Apr 2Mar 31Mar 27
24°FApr 8Apr 3Apr 1Mar 31Mar 28Mar 25Mar 21Mar 17Mar 12
20°FMar 31Mar 27Mar 22Mar 19Mar 16Mar 12Mar 9Mar 5Feb 28
16°FMar 21Mar 15Mar 12Mar 9Mar 6Mar 3Feb 28Feb 25Feb 17

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 1Oct 4Oct 7Oct 10Oct 14Oct 16Oct 19Oct 23Oct 27
32°FOct 11Oct 15Oct 18Oct 21Oct 24Oct 28Oct 31Nov 2Nov 7
28°FOct 21Oct 27Oct 30Nov 1Nov 4Nov 7Nov 10Nov 13Nov 18
24°FNov 2Nov 6Nov 11Nov 14Nov 16Nov 19Nov 23Nov 27Dec 2
20°FNov 14Nov 20Nov 24Nov 27Nov 30Dec 2Dec 5Dec 9Dec 17
16°FNov 27Dec 1Dec 4Dec 8Dec 12Dec 16Dec 20Dec 25Jan 1

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°F181174171167163160156152145
32°F203197193189186182178175168
28°F228222217212208205202198192
24°F256248243239235230226221214
20°F282274267262258254249244237
16°F304297291285281276271266258

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
5,772
Cooling degree days, base 65°F
608
Growing degree days, base 40°F
4,928
Growing degree days, base 45°F
3,737
Growing degree days, base 50°F
2,713
Growing degree days, base 55°F
1,854
Growing degree days, base 60°F
1,154

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,07601
February94100
March85904
April560037
May2699219
June5986477
July4237697
August7204662
September9467424
October3595155
November632034
December91304

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 8 km from West Wareham. 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 USC00192451 (E Wareham). Public domain.