Monson climate

Monson Frost Dates and Growing Season

NOAA 1991-2020 normals for Sebec Lake, 21.7 km from Monson, elevation 380 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Sebec Lake. 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 16 and the first fall freeze around October 1, a growing season of about 135 days.

Median at 36°F
last May 29, first September 20
Median at 32°F
last May 16, first October 1
Median at 28°F
last May 3, first October 10

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

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 6Sep 11Sep 14Sep 17Sep 20Sep 22Sep 25Sep 28Oct 2
32°FSep 19Sep 23Sep 26Sep 29Oct 1Oct 3Oct 5Oct 8Oct 12
28°FSep 29Oct 2Oct 5Oct 8Oct 10Oct 13Oct 16Oct 20Oct 26
24°FOct 9Oct 14Oct 18Oct 20Oct 24Oct 27Oct 31Nov 3Nov 8
20°FOct 23Oct 29Nov 1Nov 3Nov 6Nov 9Nov 12Nov 16Nov 20
16°FNov 4Nov 9Nov 12Nov 15Nov 18Nov 20Nov 24Nov 27Dec 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°F13012512011611311010510195
32°F153146142138135131127122115
28°F176169165161158154151145140
24°F203195190186183179175170163
20°F224218213209205201198194187
16°F243237233229226222219216210

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
8,758
Cooling degree days, base 65°F
212
Growing degree days, base 40°F
3,431
Growing degree days, base 45°F
2,520
Growing degree days, base 50°F
1,730
Growing degree days, base 55°F
1,067
Growing degree days, base 60°F
550

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,60400
February1,37800
March1,20600
April78009
May4085125
June14838343
July3989515
August6665465
September25015234
October620037
November93302
December1,32800

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 21.7 km from Monson. 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 USC00177654 (Sebec Lake). Public domain.