Winnebago climate

Winnebago Frost Dates and Growing Season

NOAA 1991-2020 normals for Winnebago, 0.5 km from Winnebago, elevation 1110 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Winnebago. 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 April 27 and the first fall freeze around October 10, a growing season of about 166 days.

Median at 36°F
last May 6, first October 1
Median at 32°F
last April 27, first October 10
Median at 28°F
last April 15, first October 20

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 18May 13May 10May 8May 6May 4May 1Apr 29Apr 23
32°FMay 8May 5May 2Apr 30Apr 27Apr 24Apr 20Apr 16Apr 10
28°FApr 29Apr 24Apr 22Apr 18Apr 15Apr 11Apr 8Apr 5Apr 1
24°FApr 21Apr 15Apr 11Apr 8Apr 6Apr 3Mar 31Mar 27Mar 21
20°FApr 13Apr 7Apr 4Apr 1Mar 30Mar 26Mar 22Mar 18Mar 13
16°FApr 6Apr 2Mar 30Mar 25Mar 22Mar 18Mar 15Mar 12Mar 8

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 19Sep 23Sep 27Sep 29Oct 1Oct 3Oct 6Oct 9Oct 14
32°FSep 27Oct 1Oct 4Oct 7Oct 10Oct 13Oct 16Oct 19Oct 23
28°FOct 5Oct 11Oct 14Oct 18Oct 20Oct 23Oct 25Oct 29Nov 1
24°FOct 16Oct 21Oct 25Oct 28Oct 30Nov 1Nov 4Nov 7Nov 12
20°FOct 26Oct 31Nov 2Nov 5Nov 8Nov 10Nov 13Nov 17Nov 22
16°FNov 2Nov 6Nov 9Nov 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°F166159154150147144140136130
32°F185179175171166162158152147
28°F207200195190186182178173166
24°F227219214210206201197192186
20°F242236230226222218213208201
16°F258251245241237233228223216

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
7,729
Cooling degree days, base 65°F
682
Growing degree days, base 40°F
4,715
Growing degree days, base 45°F
3,683
Growing degree days, base 50°F
2,756
Growing degree days, base 55°F
1,944
Growing degree days, base 60°F
1,247

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,56800
February1,28600
March1,028011
April576375
May24341291
June40157567
July9235691
August20168614
September14470386
October5077110
November935012
December1,37500

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 0.5 km from Winnebago. 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 USC00219046 (Winnebago). Public domain.