Macomb County climate

Macomb County Frost Dates and Growing Season

NOAA 1991-2020 normals for Mt Clemens Ang Base, 10.4 km from Macomb County, elevation 580 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Mt Clemens Ang Base. 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 30 and the first fall freeze around October 24, a growing season of about 174 days.

Median at 36°F
last May 11, first October 9
Median at 32°F
last April 30, first October 24
Median at 28°F
last April 18, 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 28May 23May 19May 15May 11May 8May 5May 2Apr 28
32°FMay 15May 9May 5May 2Apr 30Apr 28Apr 25Apr 21Apr 16
28°FMay 3Apr 29Apr 24Apr 21Apr 18Apr 16Apr 12Apr 8Apr 3
24°FApr 20Apr 15Apr 11Apr 7Apr 5Apr 3Mar 31Mar 28Mar 23
20°FApr 8Apr 3Apr 1Mar 30Mar 27Mar 24Mar 20Mar 17Mar 11
16°FMar 31Mar 26Mar 23Mar 19Mar 17Mar 13Mar 10Mar 6Feb 28

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 26Sep 30Oct 3Oct 6Oct 9Oct 12Oct 15Oct 19Oct 24
32°FOct 7Oct 13Oct 18Oct 21Oct 24Oct 26Oct 29Nov 1Nov 3
28°FOct 20Oct 26Oct 30Nov 1Nov 3Nov 5Nov 7Nov 10Nov 15
24°FNov 1Nov 5Nov 8Nov 10Nov 13Nov 15Nov 18Nov 22Nov 28
20°FNov 9Nov 14Nov 18Nov 21Nov 24Nov 28Dec 1Dec 4Dec 11
16°FNov 19Nov 25Nov 29Dec 2Dec 6Dec 9Dec 14Dec 18Dec 24

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°F169163158154150146142137129
32°F192185180177174170165159153
28°F216209204200196191187183177
24°F241233229224220216212208201
20°F265256250245241236232227219
16°F289281276270265260254249242

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
6,550
Cooling degree days, base 65°F
633
Growing degree days, base 40°F
4,766
Growing degree days, base 45°F
3,663
Growing degree days, base 50°F
2,703
Growing degree days, base 55°F
1,874
Growing degree days, base 60°F
1,180

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,24800
February1,08200
March939012
April569260
May26227251
June53130527
July8226684
August14178629
September12264396
October4256127
November752017
December1,07601

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 10.4 km from Macomb County. 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 USW00014804 (Mt Clemens Ang Base). Public domain.