Door County climate

Door County Frost Dates and Growing Season

NOAA 1991-2020 normals for Sturgeon Bay Exp Farm, 5 km from Door County, elevation 699 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Sturgeon Bay Exp Farm. 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 13, a growing season of about 157 days.

Median at 36°F
last May 21, first October 2
Median at 32°F
last May 8, first October 13
Median at 28°F
last April 26, 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°FJun 3May 30May 26May 23May 21May 18May 14May 11May 7
32°FMay 21May 17May 13May 10May 8May 5May 2Apr 29Apr 25
28°FMay 9May 5May 1Apr 28Apr 26Apr 23Apr 20Apr 16Apr 11
24°FApr 26Apr 22Apr 19Apr 15Apr 13Apr 10Apr 7Apr 4Mar 31
20°FApr 17Apr 12Apr 8Apr 4Apr 2Mar 31Mar 28Mar 24Mar 19
16°FApr 6Apr 3Mar 31Mar 28Mar 25Mar 22Mar 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 17Sep 23Sep 26Sep 30Oct 2Oct 5Oct 8Oct 11Oct 15
32°FSep 28Oct 3Oct 6Oct 10Oct 13Oct 17Oct 20Oct 24Oct 30
28°FOct 12Oct 17Oct 21Oct 25Oct 28Oct 31Nov 2Nov 6Nov 11
24°FOct 27Oct 31Nov 3Nov 5Nov 9Nov 12Nov 15Nov 19Nov 23
20°FNov 6Nov 10Nov 13Nov 16Nov 19Nov 22Nov 26Nov 29Dec 4
16°FNov 13Nov 18Nov 22Nov 25Nov 28Dec 1Dec 3Dec 7Dec 13

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°F152145141137134130126121114
32°F177171165161157153149144137
28°F204197192188183178173167161
24°F229222217212209204200196189
20°F249243238233229225221217211
16°F267259254250247243238233226

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
7,965
Cooling degree days, base 65°F
335
Growing degree days, base 40°F
3,843
Growing degree days, base 45°F
2,869
Growing degree days, base 50°F
2,030
Growing degree days, base 55°F
1,322
Growing degree days, base 60°F
750

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,46300
February1,26000
March1,09702
April719016
May3945138
June11749384
July29135570
August35112542
September18532307
October539167
November88104
December1,24600

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 5 km from Door County. 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 USC00478267 (Sturgeon Bay Exp Farm). Public domain.