Moretown climate

Moretown Frost Dates and Growing Season

NOAA 1991-2020 normals for Northfield, 12.7 km from Moretown, elevation 670 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Northfield. 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 18 and the first fall freeze around September 28, a growing season of about 133 days.

Median at 36°F
last May 29, first September 17
Median at 32°F
last May 18, first September 28
Median at 28°F
last May 4, first October 7

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 12Jun 7Jun 3May 31May 29May 27May 24May 20May 14
32°FMay 30May 26May 23May 20May 18May 14May 10May 7May 2
28°FMay 20May 15May 11May 7May 4May 1Apr 29Apr 26Apr 23
24°FMay 8May 1Apr 27Apr 24Apr 22Apr 20Apr 17Apr 13Apr 9
20°FApr 22Apr 18Apr 15Apr 11Apr 9Apr 7Apr 5Apr 4Apr 2
16°FApr 11Apr 7Apr 5Apr 4Apr 2Apr 1Mar 30Mar 25Mar 20

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 2Sep 7Sep 11Sep 14Sep 17Sep 20Sep 23Sep 26Sep 30
32°FSep 13Sep 19Sep 22Sep 25Sep 28Oct 1Oct 3Oct 6Oct 10
28°FSep 25Sep 30Oct 3Oct 5Oct 7Oct 10Oct 14Oct 18Oct 26
24°FOct 5Oct 9Oct 13Oct 17Oct 20Oct 24Oct 30Nov 2Nov 7
20°FOct 16Oct 24Oct 28Nov 1Nov 3Nov 7Nov 11Nov 15Nov 19
16°FNov 1Nov 6Nov 10Nov 14Nov 16Nov 19Nov 22Nov 25Nov 29

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°F1301231181141101071029788
32°F153145141136133129124119113
28°F176169164159155151147141134
24°F203197191186181177172166158
20°F226220215211208204200194187
16°F244238235231228224220215209

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
8,010
Cooling degree days, base 65°F
316
Growing degree days, base 40°F
3,841
Growing degree days, base 45°F
2,869
Growing degree days, base 50°F
2,026
Growing degree days, base 55°F
1,308
Growing degree days, base 60°F
726

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,47200
February1,26300
March1,12203
April708128
May34414186
June10660405
July30122556
August5591501
September21029282
October566159
November87806
December1,25600

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 12.7 km from Moretown. 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 USC00435733 (Northfield). Public domain.