Willsboro climate

Willsboro Frost Dates and Growing Season

NOAA 1991-2020 normals for Willsboro 1 N, 3.1 km from Willsboro, elevation 180 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Willsboro 1 N. 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 14, a growing season of about 165 days.

Median at 36°F
last May 12, first October 4
Median at 32°F
last May 2, first October 14
Median at 28°F
last April 21, first October 28

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 21May 18May 15May 12May 9May 6May 4May 1
32°FMay 16May 10May 7May 4May 2Apr 30Apr 27Apr 24Apr 20
28°FMay 3Apr 29Apr 25Apr 23Apr 21Apr 18Apr 16Apr 13Apr 9
24°FApr 22Apr 18Apr 15Apr 12Apr 9Apr 7Apr 5Apr 2Mar 30
20°FApr 14Apr 8Apr 6Apr 4Apr 2Mar 31Mar 28Mar 23Mar 18
16°FApr 5Apr 2Mar 31Mar 28Mar 24Mar 21Mar 19Mar 16Mar 12

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 26Sep 30Oct 1Oct 4Oct 6Oct 8Oct 12Oct 16
32°FOct 2Oct 5Oct 9Oct 12Oct 14Oct 17Oct 21Oct 25Nov 1
28°FOct 11Oct 17Oct 21Oct 24Oct 28Nov 1Nov 3Nov 6Nov 10
24°FOct 26Oct 31Nov 3Nov 5Nov 8Nov 11Nov 14Nov 18Nov 23
20°FNov 5Nov 9Nov 12Nov 15Nov 18Nov 21Nov 24Nov 27Dec 1
16°FNov 12Nov 17Nov 20Nov 24Nov 26Nov 30Dec 2Dec 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°F162155151147144140136131125
32°F185178173169165161157153146
28°F208201197193189184179175169
24°F229223219214211207204199193
20°F248242237233230226222218212
16°F268260255251246243239234227

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
7,301
Cooling degree days, base 65°F
513
Growing degree days, base 40°F
4,394
Growing degree days, base 45°F
3,352
Growing degree days, base 50°F
2,445
Growing degree days, base 55°F
1,658
Growing degree days, base 60°F
1,009

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,39801
February1,22200
March1,06302
April634244
May28720226
June7399476
July9190646
August24153594
September15047353
October486292
November798011
December1,15601

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 3.1 km from Willsboro. 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 USC00309495 (Willsboro 1 N). Public domain.