What the recent heat wave did to metro Detroit's fall colors

Posted at 5:46 PM, Sep 28, 2017
and last updated 2017-09-29 16:05:27-04

Part of the magic of living in southeast Michigan is the explosion of color that screams for our attention starting at around this time every year.

Like a steam train, it starts slowly, steadily picks up speed and then yells its commands to pay attention, to take pictures and just stare in awe before it races south in its annual migration. Photojournalist Josh Bowren shot this drone footage last Sunday in Holly, showing the early colors starting to pop. 

But how good the show is depends in part on our weather.

Leaves change color this time of year mainly in response to reduced amounts of sunlight. That leads to less photosynthesis, which is what gives leaves their green color.


With less green, other pigments like orange, yellow and red are produced and start showing off. But temperature and moisture levels impact the color show too.

The fall color season got off to an early start in metro Detroit, thanks to some very cool mornings in late August and early September around here. Those cool nights and sunny days are great for vibrant colors. Because of those chilly nights, early predictions were for the season to peak at least a week earlier than it did last year and earlier than long-term averages. 

Then in mid-September we started to heat up, ahead of the record-smashing heat wave that just peaked on Tuesday. We had 6 consecutive days with high temperatures around or above 90 degrees, unheard of for this late in the season.

"That heat wave has pretty much put us back on schedule," according to Bert Gregg, Associate Professor of Horticulture and Forestry at the MSU Extension. The heat put extra stress on the trees, causing some leaves to fall early and the vividness of their colors to be reduced. You might notice that trees near streets and other paved areas change earlier and can be less showy in color, due in part to the very localized hotter temperatures near them. 

But rainfall, or the relative lack of it, is playing a part too. For September, metro Detroit is more than two inches below our average rainfall. In fact the western parts of the metro area are rated "abnormally dry," the first stage of drought.

Dry soil also stresses the trees, speeding up leaf change and causing some leaves to drop early. 

So the slowdown in the leaf change that we would expect because of our heat wave is partially being countered by our dry soil conditions, which are not likely to change significantly any time soon.

The bottom line is that after our blistering week, we'll probably have a fall color season that peaks at most a little earlier than in recent years, but it will probably be a bit more muted than it would have been. "I would expect the peak of the season to be around the 3rd or 4th week of October in metro Detroit," Gregg says. So firm up those plans soon. Even if they got stressed, some of these trees will still be real show-stoppers.

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As the colors start to change, we'll see more recent photos in our online gallery. VIEW PHOTOS HERE