Racine climate

Racine Frost Dates and Growing Season

NOAA 1991-2020 normals for Ripley, 24.5 km from Racine, elevation 608 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Ripley. 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 21, a growing season of about 178 days.

Median at 36°F
last May 4, first October 11
Median at 32°F
last April 23, first October 21
Median at 28°F
last April 10, first October 31

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 19May 14May 11May 7May 4Apr 30Apr 28Apr 25Apr 21
32°FMay 11May 4Apr 30Apr 27Apr 23Apr 21Apr 18Apr 15Apr 10
28°FApr 26Apr 21Apr 17Apr 14Apr 10Apr 8Apr 4Apr 1Mar 28
24°FApr 12Apr 7Apr 4Apr 1Mar 31Mar 27Mar 24Mar 20Mar 15
20°FApr 1Mar 28Mar 24Mar 21Mar 18Mar 15Mar 10Mar 6Feb 28
16°FMar 22Mar 16Mar 12Mar 9Mar 5Mar 1Feb 26Feb 20Feb 11

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 30Oct 3Oct 5Oct 8Oct 11Oct 14Oct 16Oct 20Oct 24
32°FOct 8Oct 12Oct 15Oct 18Oct 21Oct 24Oct 27Oct 29Nov 2
28°FOct 18Oct 21Oct 24Oct 27Oct 31Nov 2Nov 4Nov 8Nov 12
24°FOct 27Nov 1Nov 3Nov 6Nov 9Nov 12Nov 15Nov 19Nov 26
20°FNov 5Nov 11Nov 14Nov 17Nov 22Nov 26Nov 30Dec 4Dec 12
16°FNov 17Nov 23Nov 28Dec 1Dec 5Dec 9Dec 16Dec 23Dec 29

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°F177171166162159154150145139
32°F198191186182178174169163156
28°F220213209206202197192187180
24°F247239234229225220216211205
20°F277268260254250245241235227
16°F306296289284278273267261251

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
4,749
Cooling degree days, base 65°F
1,109
Growing degree days, base 40°F
6,259
Growing degree days, base 45°F
4,931
Growing degree days, base 50°F
3,759
Growing degree days, base 55°F
2,732
Growing degree days, base 60°F
1,850

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,00008
February818012
March663259
April32717202
May12086435
June14215651
July0335800
August2292755
September50141542
October29721227
November597155
December863015

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 24.5 km from Racine. 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 USC00467552 (Ripley). Public domain.