Menomonee Falls climate

Menomonee Falls Frost Dates and Growing Season

NOAA 1991-2020 normals for Germantown, 6.7 km from Menomonee Falls, elevation 850 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Germantown. 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 6 and the first fall freeze around October 8, a growing season of about 154 days.

Median at 36°F
last May 19, first September 29
Median at 32°F
last May 6, first October 8
Median at 28°F
last April 24, first October 20

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 27May 23May 19May 16May 12May 7May 2
32°FMay 25May 19May 14May 10May 6May 2Apr 30Apr 26Apr 22
28°FMay 12May 5May 1Apr 27Apr 24Apr 21Apr 18Apr 14Apr 9
24°FApr 28Apr 21Apr 17Apr 13Apr 11Apr 8Apr 5Apr 2Mar 28
20°FApr 13Apr 8Apr 5Apr 2Mar 31Mar 29Mar 25Mar 22Mar 17
16°FApr 4Mar 31Mar 29Mar 25Mar 22Mar 19Mar 16Mar 12Mar 8

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 13Sep 19Sep 23Sep 26Sep 29Oct 1Oct 4Oct 7Oct 11
32°FSep 26Sep 30Oct 3Oct 5Oct 8Oct 11Oct 14Oct 18Oct 24
28°FOct 4Oct 9Oct 13Oct 16Oct 20Oct 24Oct 26Oct 29Nov 3
24°FOct 17Oct 23Oct 28Oct 30Nov 1Nov 4Nov 7Nov 11Nov 17
20°FOct 30Nov 2Nov 6Nov 9Nov 13Nov 16Nov 19Nov 23Nov 27
16°FNov 7Nov 12Nov 16Nov 19Nov 22Nov 25Nov 29Dec 3Dec 8

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°F151145140136132127123117109
32°F175168162157154149145139131
28°F200192186182178174168163155
24°F226217212207203199194189181
20°F249241235231226222218213206
16°F269260254249245240236230223

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
7,449
Cooling degree days, base 65°F
493
Growing degree days, base 40°F
4,305
Growing degree days, base 45°F
3,275
Growing degree days, base 50°F
2,381
Growing degree days, base 55°F
1,613
Growing degree days, base 60°F
974

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,41700
February1,20100
March999011
April626247
May31524215
June8594461
July21181625
August32138570
September16950342
October502598
November857012
December1,22601

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 6.7 km from Menomonee Falls. 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 USC00473058 (Germantown). Public domain.