Cedarburg climate

Cedarburg Frost Dates and Growing Season

NOAA 1991-2020 normals for Grafton Wwtp, 2.9 km from Cedarburg, elevation 741 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Grafton 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 23 and the first fall freeze around October 24, a growing season of about 182 days.

Median at 36°F
last May 5, first October 11
Median at 32°F
last April 23, first October 24
Median at 28°F
last April 11, first November 2

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 23May 17May 13May 9May 5May 2Apr 30Apr 26Apr 20
32°FMay 9May 3Apr 30Apr 27Apr 23Apr 20Apr 17Apr 15Apr 10
28°FApr 24Apr 19Apr 16Apr 14Apr 11Apr 8Apr 6Apr 3Mar 31
24°FApr 13Apr 9Apr 6Apr 3Apr 2Mar 31Mar 28Mar 23Mar 18
20°FApr 5Apr 1Mar 30Mar 26Mar 23Mar 20Mar 17Mar 13Mar 9
16°FMar 30Mar 25Mar 21Mar 18Mar 15Mar 13Mar 10Mar 7Mar 2

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 27Oct 1Oct 6Oct 9Oct 11Oct 14Oct 17Oct 21Oct 26
32°FOct 8Oct 14Oct 18Oct 21Oct 24Oct 26Oct 29Nov 1Nov 5
28°FOct 21Oct 26Oct 29Oct 31Nov 2Nov 5Nov 7Nov 11Nov 15
24°FNov 1Nov 4Nov 7Nov 10Nov 12Nov 14Nov 17Nov 21Nov 25
20°FNov 8Nov 13Nov 16Nov 19Nov 21Nov 23Nov 26Nov 30Dec 5
16°FNov 15Nov 20Nov 23Nov 26Nov 29Dec 1Dec 5Dec 11Dec 18

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°F177170165160156152149143135
32°F200194190186182178173169161
28°F223216213209205201198192186
24°F243237232228225221217213208
20°F263255251247243239235231226
16°F281272267263259255251246239

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
6,775
Cooling degree days, base 65°F
564
Growing degree days, base 40°F
4,605
Growing degree days, base 45°F
3,522
Growing degree days, base 50°F
2,586
Growing degree days, base 55°F
1,773
Growing degree days, base 60°F
1,092

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,28600
February1,09700
March944011
April596142
May29717216
June6789473
July10213668
August16178628
September11662399
October4214134
November786016
December1,13800

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 2.9 km from Cedarburg. 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 USC00473198 (Grafton Wwtp). Public domain.