Bayfield County climate

Bayfield County Frost Dates and Growing Season

NOAA 1991-2020 normals for Ashland Kennedy Mem AP, 22.2 km from Bayfield County, elevation 826 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Ashland Kennedy Mem AP. 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 23 and the first fall freeze around September 29, a growing season of about 125 days.

Median at 36°F
last June 4, first September 17
Median at 32°F
last May 23, first September 29
Median at 28°F
last May 8, 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 18Jun 13Jun 9Jun 6Jun 4Jun 2May 31May 27May 23
32°FJun 6Jun 2May 29May 25May 23May 20May 17May 13May 8
28°FMay 23May 19May 15May 11May 8May 5May 1Apr 29Apr 25
24°FMay 10May 5May 1Apr 29Apr 25Apr 23Apr 20Apr 17Apr 12
20°FApr 27Apr 23Apr 20Apr 17Apr 15Apr 11Apr 8Apr 4Apr 1
16°FApr 20Apr 15Apr 11Apr 7Apr 5Apr 2Mar 31Mar 27Mar 22

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 1Sep 5Sep 10Sep 14Sep 17Sep 20Sep 23Sep 26Oct 1
32°FSep 14Sep 20Sep 23Sep 26Sep 29Oct 1Oct 4Oct 7Oct 11
28°FSep 25Sep 30Oct 3Oct 6Oct 9Oct 12Oct 15Oct 19Oct 24
24°FOct 6Oct 11Oct 15Oct 19Oct 23Oct 26Oct 30Nov 1Nov 6
20°FOct 19Oct 25Oct 30Nov 1Nov 3Nov 6Nov 9Nov 12Nov 17
16°FOct 31Nov 3Nov 7Nov 11Nov 13Nov 16Nov 19Nov 23Nov 28

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°F12111511010610298948880
32°F146139133129125121117112104
28°F173166161156152147142137129
24°F199192186183178173168162156
20°F222215210207202198194189182
16°F240234230225221217213209202

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
8,796
Cooling degree days, base 65°F
259
Growing degree days, base 40°F
3,482
Growing degree days, base 45°F
2,561
Growing degree days, base 50°F
1,775
Growing degree days, base 55°F
1,118
Growing degree days, base 60°F
604

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,57900
February1,34000
March1,15204
April764019
May4278127
June16139333
July57110518
August7075470
September25325247
October620253
November98105
December1,39200

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 22.2 km from Bayfield County. 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 USW00094929 (Ashland Kennedy Mem AP). Public domain.