Leverett climate

Leverett Frost Dates and Growing Season

NOAA 1991-2020 normals for Leverett #2, 2.5 km from Leverett, elevation 315 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Leverett #2. 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 2 and the first fall freeze around October 9, a growing season of about 160 days.

Median at 36°F
last May 13, first September 30
Median at 32°F
last May 2, first October 9
Median at 28°F
last April 21, first October 23

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 26May 22May 19May 16May 13May 10May 8May 4Apr 30
32°FMay 16May 11May 7May 5May 2Apr 30Apr 27Apr 25Apr 21
28°FMay 4Apr 28Apr 25Apr 23Apr 21Apr 19Apr 16Apr 12Apr 8
24°FApr 20Apr 16Apr 13Apr 11Apr 8Apr 6Apr 4Apr 2Mar 29
20°FApr 8Apr 4Apr 2Mar 31Mar 29Mar 27Mar 22Mar 19Mar 14
16°FApr 1Mar 29Mar 24Mar 21Mar 19Mar 16Mar 13Mar 11Mar 7

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 17Sep 22Sep 25Sep 27Sep 30Oct 1Oct 4Oct 7Oct 11
32°FSep 29Oct 1Oct 4Oct 6Oct 9Oct 12Oct 16Oct 20Oct 25
28°FOct 7Oct 12Oct 16Oct 20Oct 23Oct 26Oct 29Nov 1Nov 4
24°FOct 21Oct 26Oct 29Nov 1Nov 3Nov 6Nov 8Nov 12Nov 16
20°FNov 1Nov 5Nov 8Nov 11Nov 14Nov 17Nov 19Nov 23Nov 28
16°FNov 11Nov 15Nov 18Nov 21Nov 24Nov 27Dec 1Dec 4Dec 11

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°F155150145142139135132127121
32°F179173168164160157153148142
28°F203197192188184180176172165
24°F224219214211208204201196189
20°F250244239234230226222217211
16°F271263259254250245241237230

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
6,968
Cooling degree days, base 65°F
588
Growing degree days, base 40°F
4,595
Growing degree days, base 45°F
3,535
Growing degree days, base 50°F
2,606
Growing degree days, base 55°F
1,800
Growing degree days, base 60°F
1,124

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,36400
February1,16900
March96608
April568361
May25424260
June56104499
July8220677
August13179631
September14556364
October480295
November807010
December1,13901

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 2.5 km from Leverett. 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 USC00194154 (Leverett #2). Public domain.