Greenville climate

Greenville Frost Dates and Growing Season

NOAA 1991-2020 normals for Greenville Maine Forestry Svc, 0.4 km from Greenville, elevation 1037 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Greenville Maine Forestry Svc. 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 9, a growing season of about 153 days.

Median at 36°F
last May 21, first September 29
Median at 32°F
last May 7, first October 9
Median at 28°F
last April 28, first October 22

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 2May 30May 26May 23May 21May 18May 16May 12May 7
32°FMay 20May 16May 13May 9May 7May 5May 3May 1Apr 27
28°FMay 7May 4May 2Apr 30Apr 28Apr 25Apr 23Apr 20Apr 15
24°FApr 28Apr 24Apr 22Apr 19Apr 17Apr 14Apr 12Apr 8Apr 5
20°FApr 20Apr 16Apr 13Apr 10Apr 8Apr 6Apr 4Apr 2Mar 30
16°FApr 13Apr 8Apr 6Apr 4Apr 2Apr 1Mar 30Mar 27Mar 22

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 18Sep 22Sep 24Sep 27Sep 29Oct 1Oct 3Oct 6Oct 10
32°FSep 27Oct 1Oct 3Oct 6Oct 9Oct 12Oct 15Oct 19Oct 24
28°FOct 7Oct 12Oct 16Oct 20Oct 22Oct 26Oct 29Nov 1Nov 4
24°FOct 20Oct 26Oct 29Nov 1Nov 2Nov 5Nov 7Nov 11Nov 15
20°FNov 1Nov 4Nov 7Nov 10Nov 12Nov 15Nov 18Nov 21Nov 25
16°FNov 9Nov 13Nov 15Nov 18Nov 21Nov 23Nov 25Nov 28Dec 3

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°F148143138134130127124119114
32°F171165160156153150146141136
28°F195190185181177174169165158
24°F215210206202199195192188181
20°F234228224220217213210206200
16°F250243238235231228225220214

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
8,860
Cooling degree days, base 65°F
200
Growing degree days, base 40°F
3,383
Growing degree days, base 45°F
2,481
Growing degree days, base 50°F
1,698
Growing degree days, base 55°F
1,039
Growing degree days, base 60°F
530

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,57600
February1,36400
March1,22102
April812011
May4276120
June16031325
July4585505
August6760459
September25117234
October624140
November96303
December1,35000

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 0.4 km from Greenville. 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 USW00094626 (Greenville Maine Forestry Svc). Public domain.