Wilkin County climate

Wilkin County Frost Dates and Growing Season

NOAA 1991-2020 normals for Rothsay, 19.6 km from Wilkin County, elevation 1204 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Rothsay. 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 5 and the first fall freeze around October 3, a growing season of about 149 days.

Median at 36°F
last May 15, first September 25
Median at 32°F
last May 5, first October 3
Median at 28°F
last April 28, first October 12

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 30May 25May 21May 18May 15May 13May 10May 7May 3
32°FMay 20May 14May 11May 8May 5May 3May 1Apr 29Apr 24
28°FMay 10May 5May 2Apr 30Apr 28Apr 25Apr 22Apr 18Apr 13
24°FMay 2Apr 29Apr 24Apr 22Apr 19Apr 15Apr 12Apr 9Apr 5
20°FApr 25Apr 20Apr 17Apr 13Apr 10Apr 8Apr 5Apr 3Mar 30
16°FApr 17Apr 12Apr 9Apr 6Apr 4Apr 2Mar 31Mar 27Mar 20

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 16Sep 19Sep 22Sep 25Sep 27Sep 29Oct 2Oct 6
32°FSep 21Sep 26Sep 29Oct 1Oct 3Oct 5Oct 8Oct 12Oct 17
28°FSep 28Oct 2Oct 5Oct 9Oct 12Oct 15Oct 18Oct 22Oct 25
24°FOct 5Oct 10Oct 15Oct 18Oct 21Oct 24Oct 27Oct 31Nov 4
20°FOct 14Oct 20Oct 25Oct 28Oct 31Nov 2Nov 5Nov 8Nov 14
16°FOct 24Oct 30Nov 1Nov 4Nov 7Nov 10Nov 13Nov 17Nov 22

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°F149143138134131128124119113
32°F166160156152149145142137131
28°F187180174170166162158153148
24°F206200194189184180176171164
20°F222215210206203199195189182
16°F238230225220217213209205198

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
8,937
Cooling degree days, base 65°F
478
Growing degree days, base 40°F
4,103
Growing degree days, base 45°F
3,153
Growing degree days, base 50°F
2,308
Growing degree days, base 55°F
1,571
Growing degree days, base 60°F
954

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,74700
February1,46200
March1,18602
April691136
May30224235
June67100484
July20175620
August33134566
September20642304
October627259
November1,06703
December1,53100

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 19.6 km from Wilkin 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 USC00217149 (Rothsay). Public domain.