Windsor climate

Windsor Frost Dates and Growing Season

NOAA 1991-2020 normals for Newport, 20 km from Windsor, elevation 770 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Newport. 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 14 and the first fall freeze around October 1, a growing season of about 140 days.

Median at 36°F
last May 27, first September 21
Median at 32°F
last May 14, first October 1
Median at 28°F
last May 1, first October 11

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 8Jun 4Jun 1May 29May 27May 24May 21May 17May 12
32°FMay 29May 23May 20May 17May 14May 10May 7May 4Apr 30
28°FMay 17May 10May 7May 4May 1Apr 29Apr 27Apr 24Apr 19
24°FMay 3Apr 28Apr 25Apr 22Apr 19Apr 17Apr 13Apr 9Apr 4
20°FApr 20Apr 15Apr 12Apr 9Apr 7Apr 4Apr 2Apr 1Mar 27
16°FApr 10Apr 6Apr 3Apr 2Mar 31Mar 29Mar 25Mar 21Mar 15

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 15Sep 18Sep 21Sep 23Sep 26Sep 29Oct 2
32°FSep 19Sep 24Sep 27Sep 30Oct 1Oct 3Oct 5Oct 8Oct 12
28°FOct 1Oct 3Oct 6Oct 8Oct 11Oct 13Oct 16Oct 21Oct 28
24°FOct 7Oct 12Oct 16Oct 19Oct 22Oct 25Oct 30Nov 2Nov 7
20°FOct 20Oct 25Oct 29Nov 1Nov 4Nov 8Nov 11Nov 16Nov 21
16°FNov 1Nov 7Nov 11Nov 15Nov 18Nov 22Nov 25Nov 29Dec 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°F13612912512011711311010698
32°F158152148144140137132127121
28°F182176171167163159155150143
24°F208201196191187182178172164
20°F232224219214211207203197188
16°F253246241237233228223219212

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
7,835
Cooling degree days, base 65°F
329
Growing degree days, base 40°F
3,848
Growing degree days, base 45°F
2,869
Growing degree days, base 50°F
2,021
Growing degree days, base 55°F
1,309
Growing degree days, base 60°F
738

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,42000
February1,22600
March1,09403
April690128
May34911172
June11460398
July30130566
August5095510
September21630279
October567259
November86707
December1,21200

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 20 km from Windsor. 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 USC00275868 (Newport). Public domain.