Oak Creek climate

Oak Creek Frost Dates and Growing Season

NOAA 1991-2020 normals for South Milwaukee Wwtp, 2 km from Oak Creek, elevation 650 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for South Milwaukee Wwtp. 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 22 and the first fall freeze around October 26, a growing season of about 184 days.

Median at 36°F
last May 5, first October 16
Median at 32°F
last April 22, first October 26
Median at 28°F
last April 9, first November 5

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 24May 18May 12May 8May 5May 2Apr 30Apr 26Apr 21
32°FMay 8May 1Apr 29Apr 25Apr 22Apr 19Apr 16Apr 13Apr 9
28°FApr 24Apr 19Apr 16Apr 13Apr 9Apr 7Apr 5Apr 2Mar 28
24°FApr 13Apr 8Apr 5Apr 2Mar 31Mar 28Mar 25Mar 21Mar 15
20°FApr 2Mar 29Mar 26Mar 22Mar 19Mar 16Mar 14Mar 10Mar 6
16°FMar 25Mar 20Mar 16Mar 13Mar 10Mar 8Mar 5Mar 2Feb 25

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°FOct 1Oct 7Oct 10Oct 14Oct 16Oct 19Oct 22Oct 25Oct 28
32°FOct 10Oct 16Oct 20Oct 24Oct 26Oct 28Oct 31Nov 3Nov 8
28°FOct 24Oct 30Nov 1Nov 3Nov 5Nov 8Nov 11Nov 15Nov 20
24°FNov 3Nov 6Nov 9Nov 12Nov 15Nov 18Nov 22Nov 26Dec 1
20°FNov 9Nov 13Nov 18Nov 21Nov 24Nov 27Dec 1Dec 4Dec 11
16°FNov 17Nov 23Nov 27Dec 1Dec 3Dec 6Dec 10Dec 15Dec 21

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°F179174169165162157153148140
32°F203196192188184180176171163
28°F226220216212208205200195188
24°F249242237233229225221217210
20°F271264259254250245240234225
16°F289280274270265261257251244

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
6,679
Cooling degree days, base 65°F
661
Growing degree days, base 40°F
4,773
Growing degree days, base 45°F
3,669
Growing degree days, base 50°F
2,716
Growing degree days, base 55°F
1,900
Growing degree days, base 60°F
1,210

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,29700
February1,10201
March932010
April599142
May30315210
June75102478
July8242699
August7216674
September9579436
October3995143
November744022
December1,11701

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 2 km from Oak Creek. 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 USC00477964 (South Milwaukee Wwtp). Public domain.