Webster climate

Webster Frost Dates and Growing Season

NOAA 1991-2020 normals for Danbury, 14.5 km from Webster, elevation 950 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Danbury. 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 11 and the first fall freeze around September 30, a growing season of about 138 days.

Median at 36°F
last May 26, first September 20
Median at 32°F
last May 11, first September 30
Median at 28°F
last April 30, first October 9

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 10Jun 4Jun 1May 30May 26May 23May 20May 16May 10
32°FMay 28May 23May 18May 14May 11May 8May 5May 1Apr 28
28°FMay 16May 10May 6May 3Apr 30Apr 28Apr 25Apr 22Apr 17
24°FMay 5Apr 30Apr 27Apr 25Apr 21Apr 18Apr 15Apr 12Apr 7
20°FApr 25Apr 21Apr 18Apr 14Apr 11Apr 7Apr 5Apr 2Mar 29
16°FApr 17Apr 12Apr 7Apr 5Apr 2Mar 31Mar 29Mar 24Mar 19

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 4Sep 10Sep 13Sep 17Sep 20Sep 23Sep 26Sep 29Oct 3
32°FSep 15Sep 20Sep 24Sep 27Sep 30Oct 2Oct 5Oct 8Oct 13
28°FSep 25Oct 1Oct 3Oct 6Oct 9Oct 12Oct 16Oct 20Oct 25
24°FOct 6Oct 11Oct 16Oct 19Oct 22Oct 25Oct 28Nov 1Nov 5
20°FOct 17Oct 23Oct 27Oct 30Nov 2Nov 4Nov 7Nov 11Nov 16
16°FOct 28Nov 1Nov 5Nov 7Nov 10Nov 13Nov 16Nov 19Nov 24

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°F13713012512111711310910396
32°F159153147143138134130124117
28°F179173169165160156152147140
24°F201194190185181177173168161
20°F222216211207204199194188181
16°F239232227224220216212208201

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
8,500
Cooling degree days, base 65°F
409
Growing degree days, base 40°F
3,976
Growing degree days, base 45°F
3,016
Growing degree days, base 50°F
2,170
Growing degree days, base 55°F
1,443
Growing degree days, base 60°F
849

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,64600
February1,34500
March1,10504
April672141
May31822215
June10276427
July30154589
August50114529
September21640294
October595367
November99005
December1,43200

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 14.5 km from Webster. 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 USC00471978 (Danbury). Public domain.