Washburn climate

Washburn Frost Dates and Growing Season

NOAA 1991-2020 normals for Madeline Island, 15.3 km from Washburn, elevation 660 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Madeline Island. 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 20 and the first fall freeze around October 9, a growing season of about 140 days.

Median at 36°F
last June 1, first September 29
Median at 32°F
last May 20, first October 9
Median at 28°F
last May 6, first October 23

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 13Jun 8Jun 5Jun 3Jun 1May 30May 27May 24May 20
32°FJun 3May 30May 26May 23May 20May 17May 14May 10May 5
28°FMay 21May 17May 12May 9May 6May 3Apr 30Apr 28Apr 24
24°FMay 8May 2Apr 30Apr 27Apr 24Apr 22Apr 19Apr 15Apr 10
20°FApr 25Apr 21Apr 18Apr 15Apr 12Apr 9Apr 7Apr 4Apr 1
16°FApr 18Apr 11Apr 8Apr 6Apr 3Apr 1Mar 30Mar 27Mar 21

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 17Sep 21Sep 24Sep 27Sep 29Oct 1Oct 4Oct 7Oct 11
32°FSep 25Oct 1Oct 4Oct 6Oct 9Oct 12Oct 15Oct 19Oct 23
28°FOct 6Oct 12Oct 16Oct 20Oct 23Oct 25Oct 28Nov 1Nov 4
24°FOct 21Oct 26Oct 30Nov 1Nov 3Nov 6Nov 9Nov 13Nov 17
20°FNov 1Nov 4Nov 8Nov 11Nov 14Nov 17Nov 20Nov 24Nov 28
16°FNov 8Nov 13Nov 17Nov 20Nov 23Nov 25Nov 28Dec 1Dec 6

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°F135129125121118115111107100
32°F161155149144140136131127120
28°F186180175171166162158153144
24°F212205200195191188183178171
20°F234228223219216212208203196
16°F249244240235232229224219213

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
8,855
Cooling degree days, base 65°F
244
Growing degree days, base 40°F
3,397
Growing degree days, base 45°F
2,498
Growing degree days, base 50°F
1,731
Growing degree days, base 55°F
1,090
Growing degree days, base 60°F
589

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,56800
February1,35800
March1,19401
April809012
May4774100
June19030300
July58101508
August5585494
September22923262
October610149
November96204
December1,34700

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 15.3 km from Washburn. 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 USC00474953 (Madeline Island). Public domain.