McGregor climate

McGregor Frost Dates and Growing Season

NOAA 1991-2020 normals for Prairie Du Chien, 5.4 km from McGregor, elevation 658 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Prairie Du Chien. 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 28 and the first fall freeze around October 12, a growing season of about 166 days.

Median at 36°F
last May 7, first October 2
Median at 32°F
last April 28, first October 12
Median at 28°F
last April 16, first October 22

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 21May 17May 13May 10May 7May 5May 1Apr 29Apr 22
32°FMay 11May 6May 3Apr 30Apr 28Apr 25Apr 22Apr 18Apr 14
28°FMay 2Apr 27Apr 23Apr 19Apr 16Apr 13Apr 10Apr 6Apr 2
24°FApr 21Apr 15Apr 10Apr 7Apr 4Apr 2Mar 31Mar 27Mar 21
20°FApr 10Apr 4Apr 1Mar 30Mar 27Mar 23Mar 19Mar 15Mar 10
16°FMar 31Mar 27Mar 23Mar 20Mar 17Mar 14Mar 11Mar 7Mar 3

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 24Sep 27Sep 30Oct 2Oct 5Oct 7Oct 11Oct 15
32°FSep 27Oct 2Oct 6Oct 9Oct 12Oct 14Oct 17Oct 20Oct 25
28°FOct 7Oct 13Oct 16Oct 19Oct 22Oct 25Oct 28Oct 31Nov 4
24°FOct 20Oct 24Oct 28Oct 30Nov 1Nov 3Nov 7Nov 11Nov 16
20°FOct 31Nov 2Nov 5Nov 9Nov 12Nov 16Nov 19Nov 22Nov 28
16°FNov 6Nov 11Nov 14Nov 18Nov 22Nov 25Nov 28Dec 2Dec 7

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°F165159155151147143139135128
32°F185178174169166162158153146
28°F208201195191187183179174167
24°F230222217213209205200195187
20°F253245238234229225221216210
16°F270262257252249243239233226

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
7,015
Cooling degree days, base 65°F
748
Growing degree days, base 40°F
4,944
Growing degree days, base 45°F
3,863
Growing degree days, base 50°F
2,900
Growing degree days, base 55°F
2,058
Growing degree days, base 60°F
1,337

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,44400
February1,18400
March934117
April525382
May22242303
June33160577
July5256716
August12203656
September13073399
October44710133
November839017
December1,24001

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 5.4 km from McGregor. 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 USC00476827 (Prairie Du Chien). Public domain.