Windsor climate

Windsor Frost Dates and Growing Season

NOAA 1991-2020 normals for Gardiner, 19.4 km from Windsor, elevation 133 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Gardiner. 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 1 and the first fall freeze around October 11, a growing season of about 163 days.

Median at 36°F
last May 14, first October 1
Median at 32°F
last May 1, first October 11
Median at 28°F
last April 19, first October 25

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 27May 22May 18May 16May 14May 11May 8May 4May 1
32°FMay 14May 8May 5May 3May 1Apr 29Apr 27Apr 24Apr 20
28°FApr 30Apr 26Apr 24Apr 21Apr 19Apr 16Apr 14Apr 11Apr 8
24°FApr 20Apr 15Apr 12Apr 10Apr 8Apr 6Apr 4Apr 2Mar 31
20°FApr 8Apr 5Apr 3Apr 2Mar 31Mar 29Mar 25Mar 21Mar 17
16°FApr 3Mar 31Mar 28Mar 25Mar 22Mar 19Mar 17Mar 14Mar 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 21Sep 25Sep 28Sep 30Oct 1Oct 4Oct 5Oct 9Oct 13
32°FSep 30Oct 2Oct 6Oct 8Oct 11Oct 14Oct 17Oct 22Oct 28
28°FOct 11Oct 15Oct 18Oct 22Oct 25Oct 28Nov 1Nov 4Nov 8
24°FOct 23Oct 28Nov 1Nov 4Nov 6Nov 9Nov 12Nov 15Nov 20
20°FNov 5Nov 10Nov 13Nov 16Nov 19Nov 22Nov 24Nov 28Dec 2
16°FNov 15Nov 20Nov 24Nov 27Nov 29Dec 1Dec 3Dec 6Dec 12

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°F157152147144141137133129123
32°F182175170167163159155151144
28°F207201196192189185181176171
24°F228223219215212209205201194
20°F251246241238234230226223217
16°F269263259255251248244239234

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
7,375
Cooling degree days, base 65°F
427
Growing degree days, base 40°F
4,203
Growing degree days, base 45°F
3,171
Growing degree days, base 50°F
2,276
Growing degree days, base 55°F
1,515
Growing degree days, base 60°F
894

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,40100
February1,21100
March1,04903
April647026
May31810185
June8865428
July13169622
August19141587
September15840336
October493281
November80608
December1,17300

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 19.4 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 USC00173046 (Gardiner). Public domain.