Worcester climate

Worcester Frost Dates and Growing Season

NOAA 1991-2020 normals for Cooperstown, 20 km from Worcester, elevation 1257 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Cooperstown. 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 7 and the first fall freeze around October 7, a growing season of about 154 days.

Median at 36°F
last May 20, first September 30
Median at 32°F
last May 7, first October 7
Median at 28°F
last April 25, 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°FJun 3May 30May 27May 24May 20May 16May 12May 8May 1
32°FMay 26May 20May 16May 12May 7May 3Apr 30Apr 27Apr 22
28°FMay 12May 5May 1Apr 28Apr 25Apr 22Apr 19Apr 15Apr 9
24°FApr 27Apr 21Apr 17Apr 15Apr 11Apr 8Apr 5Apr 3Mar 30
20°FApr 15Apr 10Apr 6Apr 4Apr 2Mar 31Mar 29Mar 25Mar 20
16°FApr 6Apr 3Mar 31Mar 29Mar 26Mar 23Mar 20Mar 16Mar 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°FSep 16Sep 21Sep 24Sep 27Sep 30Oct 2Oct 4Oct 7Oct 13
32°FSep 24Sep 29Oct 2Oct 4Oct 7Oct 10Oct 14Oct 18Oct 24
28°FOct 3Oct 8Oct 12Oct 16Oct 21Oct 25Oct 30Nov 2Nov 7
24°FOct 14Oct 25Oct 30Nov 1Nov 4Nov 8Nov 11Nov 14Nov 20
20°FNov 1Nov 5Nov 9Nov 12Nov 15Nov 18Nov 22Nov 26Dec 2
16°FNov 10Nov 14Nov 18Nov 22Nov 25Nov 29Dec 1Dec 6Dec 13

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°F152145140136131127122118112
32°F175168163158154149144138131
28°F200192187183178174169163154
24°F227220214210205201196190181
20°F248242236231227223219213206
16°F267259253249245241236231224

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
8,232
Cooling degree days, base 65°F
188
Growing degree days, base 40°F
3,514
Growing degree days, base 45°F
2,554
Growing degree days, base 50°F
1,736
Growing degree days, base 55°F
1,053
Growing degree days, base 60°F
524

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,44300
February1,25600
March1,13603
April719128
May3918151
June14736343
July5378490
August8153437
September25313230
October602049
November91205
December1,24000

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 20 km from Worcester. 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 USC00301752 (Cooperstown). Public domain.