Mount Pleasant climate

Mount Pleasant Frost Dates and Growing Season

NOAA 1991-2020 normals for Racine, 5.7 km from Mount Pleasant, elevation 595 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Racine. 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 20 and the first fall freeze around October 24, a growing season of about 184 days.

Median at 36°F
last May 4, first October 13
Median at 32°F
last April 20, first October 24
Median at 28°F
last April 9, first November 3

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 15May 10May 7May 4May 2Apr 29Apr 25Apr 20
32°FMay 6May 1Apr 27Apr 23Apr 20Apr 17Apr 15Apr 11Apr 7
28°FApr 23Apr 19Apr 15Apr 11Apr 9Apr 6Apr 4Apr 1Mar 28
24°FApr 12Apr 7Apr 4Apr 2Mar 31Mar 28Mar 24Mar 20Mar 15
20°FApr 3Mar 31Mar 27Mar 24Mar 21Mar 18Mar 14Mar 11Mar 6
16°FMar 26Mar 22Mar 19Mar 15Mar 12Mar 9Mar 6Mar 2Feb 26

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 29Oct 3Oct 7Oct 10Oct 13Oct 17Oct 20Oct 23Oct 27
32°FOct 8Oct 15Oct 18Oct 21Oct 24Oct 27Oct 30Nov 1Nov 5
28°FOct 19Oct 26Oct 29Nov 1Nov 3Nov 6Nov 8Nov 12Nov 16
24°FNov 1Nov 4Nov 7Nov 9Nov 12Nov 15Nov 18Nov 21Nov 26
20°FNov 7Nov 11Nov 15Nov 18Nov 21Nov 24Nov 27Dec 1Dec 6
16°FNov 13Nov 19Nov 23Nov 26Nov 29Dec 2Dec 6Dec 10Dec 17

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°F180174169166161157152147139
32°F203198192189184180175170162
28°F225219214211207203199193186
24°F248241237232228224220215209
20°F269261255250246242239235227
16°F285278272267263258254248242

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
7,040
Cooling degree days, base 65°F
523
Growing degree days, base 40°F
4,399
Growing degree days, base 45°F
3,339
Growing degree days, base 50°F
2,433
Growing degree days, base 55°F
1,659
Growing degree days, base 60°F
1,020

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,33100
February1,11600
March96605
April644031
May3668155
June10376425
July12198651
August13178631
September11760397
October4383121
November785015
December1,15001

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 5.7 km from Mount Pleasant. 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 USC00476922 (Racine). Public domain.