Wisconsin Dells climate

Wisconsin Dells Frost Dates and Growing Season

NOAA 1991-2020 normals for Wisconsin Dells, 2.2 km from Wisconsin Dells, elevation 835 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Wisconsin Dells. 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 8 and the first fall freeze around October 3, a growing season of about 146 days.

Median at 36°F
last May 18, first September 25
Median at 32°F
last May 8, first October 3
Median at 28°F
last April 28, first October 14

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 2May 28May 25May 22May 18May 16May 13May 8May 4
32°FMay 22May 17May 14May 11May 8May 4May 2Apr 29Apr 24
28°FMay 13May 8May 3Apr 30Apr 28Apr 25Apr 21Apr 18Apr 13
24°FMay 2Apr 27Apr 23Apr 20Apr 16Apr 13Apr 10Apr 6Apr 2
20°FApr 20Apr 14Apr 9Apr 6Apr 4Apr 2Mar 30Mar 25Mar 20
16°FApr 8Apr 3Apr 1Mar 30Mar 26Mar 23Mar 20Mar 16Mar 11

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 12Sep 17Sep 20Sep 23Sep 25Sep 28Sep 30Oct 3Oct 6
32°FSep 21Sep 26Sep 29Oct 1Oct 3Oct 5Oct 8Oct 12Oct 16
28°FSep 30Oct 4Oct 7Oct 10Oct 14Oct 16Oct 19Oct 23Oct 28
24°FOct 8Oct 15Oct 18Oct 22Oct 25Oct 28Oct 31Nov 2Nov 6
20°FOct 23Oct 28Oct 31Nov 2Nov 4Nov 7Nov 11Nov 15Nov 20
16°FNov 1Nov 5Nov 8Nov 11Nov 15Nov 18Nov 21Nov 25Nov 30

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°F146140136131127124120116110
32°F167160155150146143139135128
28°F188182177172168164161155149
24°F212204199195190187183177170
20°F237228222218214210206200193
16°F256248243239235231226221215

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
7,570
Cooling degree days, base 65°F
563
Growing degree days, base 40°F
4,446
Growing degree days, base 45°F
3,421
Growing degree days, base 50°F
2,517
Growing degree days, base 55°F
1,738
Growing degree days, base 60°F
1,079

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,48200
February1,22800
March1,006011
April603358
May27132256
June57124518
July14202652
August29148584
September17550337
October526592
November89709
December1,28500

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 2.2 km from Wisconsin Dells. 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 USC00479319 (Wisconsin Dells). Public domain.