Osterville climate

Osterville Frost Dates and Growing Season

NOAA 1991-2020 normals for Hyannis, 8 km from Osterville, elevation 60 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Hyannis. 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 16 and the first fall freeze around October 30, a growing season of about 195 days.

Median at 36°F
last April 29, first October 19
Median at 32°F
last April 16, first October 30
Median at 28°F
last April 3, first November 11

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 13May 7May 3May 1Apr 29Apr 26Apr 23Apr 20Apr 16
32°FApr 30Apr 25Apr 22Apr 19Apr 16Apr 13Apr 10Apr 8Apr 5
28°FApr 15Apr 10Apr 7Apr 5Apr 3Apr 2Mar 31Mar 28Mar 22
24°FApr 4Apr 1Mar 30Mar 27Mar 24Mar 20Mar 17Mar 15Mar 9
20°FMar 26Mar 22Mar 18Mar 16Mar 13Mar 10Mar 6Mar 3Feb 27
16°FMar 19Mar 14Mar 10Mar 6Mar 3Mar 1Feb 25Feb 21Feb 11

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 5Oct 10Oct 14Oct 17Oct 19Oct 22Oct 25Oct 28Nov 2
32°FOct 15Oct 20Oct 24Oct 27Oct 30Nov 1Nov 4Nov 7Nov 13
28°FOct 29Nov 2Nov 5Nov 8Nov 11Nov 14Nov 17Nov 22Nov 30
24°FNov 8Nov 14Nov 17Nov 21Nov 25Nov 28Dec 1Dec 5Dec 11
20°FNov 21Nov 27Dec 1Dec 3Dec 6Dec 10Dec 14Dec 19Dec 26
16°FDec 2Dec 8Dec 13Dec 17Dec 22Dec 25Dec 28Jan 2Jan 10

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°F191185181176172168164159152
32°F215209204199195192187183175
28°F241235229225221217212209203
24°F269261255249245241236231225
20°F293285279274270264259254246
16°F314307302297291287281275267

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
5,819
Cooling degree days, base 65°F
494
Growing degree days, base 40°F
4,729
Growing degree days, base 45°F
3,530
Growing degree days, base 50°F
2,518
Growing degree days, base 55°F
1,680
Growing degree days, base 60°F
1,006

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,06800
February93500
March87103
April573031
May3105178
June8562428
July7198656
August11169623
September9256415
October3594152
November615031
December89303

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 Osterville. 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 USC00193821 (Hyannis). Public domain.