North Windham climate

North Windham Frost Dates and Growing Season

NOAA 1991-2020 normals for Windham 2NW, 3.4 km from North Windham, elevation 443 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Windham 2NW. 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 April 30 and the first fall freeze around October 20, a growing season of about 172 days.

Median at 36°F
last May 11, first October 7
Median at 32°F
last April 30, first October 20
Median at 28°F
last April 17, first November 1

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 22May 19May 15May 13May 11May 8May 5May 2Apr 29
32°FMay 12May 7May 4May 1Apr 30Apr 28Apr 25Apr 22Apr 18
28°FApr 29Apr 24Apr 22Apr 19Apr 17Apr 15Apr 12Apr 9Apr 5
24°FApr 18Apr 13Apr 9Apr 7Apr 5Apr 4Apr 2Mar 31Mar 26
20°FApr 8Apr 5Apr 3Apr 1Mar 30Mar 28Mar 23Mar 20Mar 16
16°FApr 2Mar 31Mar 28Mar 24Mar 21Mar 19Mar 16Mar 13Mar 10

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 28Oct 1Oct 3Oct 5Oct 7Oct 10Oct 13Oct 17Oct 23
32°FOct 5Oct 9Oct 13Oct 16Oct 20Oct 22Oct 26Oct 30Nov 3
28°FOct 17Oct 22Oct 26Oct 30Nov 1Nov 4Nov 7Nov 11Nov 16
24°FNov 1Nov 4Nov 8Nov 11Nov 13Nov 16Nov 19Nov 23Nov 27
20°FNov 10Nov 14Nov 17Nov 21Nov 24Nov 27Nov 30Dec 3Dec 9
16°FNov 18Nov 24Nov 27Nov 30Dec 1Dec 5Dec 8Dec 12Dec 17

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°F166161157152149146143139134
32°F190184180176172168164159153
28°F216209204201197194189185179
24°F238232228224220217214209203
20°F258252247243239236232228222
16°F274268263260256253249244237

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
7,434
Cooling degree days, base 65°F
447
Growing degree days, base 40°F
4,216
Growing degree days, base 45°F
3,198
Growing degree days, base 50°F
2,308
Growing degree days, base 55°F
1,551
Growing degree days, base 60°F
931

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,40100
February1,21500
March1,07706
April663025
May3328173
June8270439
July10171626
August11147601
September14849354
October499176
November82407
December1,17200

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 3.4 km from North Windham. 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 USC00179720 (Windham 2NW). Public domain.