We're on track for a colorful fall in the suburbs

With the explosive colors of summer fireworks behind us, anticipation of the bright displays of fall foliage has returned to the suburbs.

Mother Nature's own summer fireworks - in the form of the especially stormy weather the region experienced - won't have as much impact on the changing of the leaves as the sunshine and temperatures yet to come, said Ed Hedborn, fall color scout for the Morton Arboretum in Lisle.

"You need a healthy plant going into fall to really display the fall colors," Hedborn said.

That's why fall is more likely to be affected by a summer with too little rain than too much, he said.

"It looks like we're on track for good fall colors with lots of reds," Hedborn said.

His job, though, requires frequent, direct observation of the trees and constant updates on changing weather conditions. Long-term weather forecasts aren't accurate enough to base an entire fall outlook on them.

The best colors are triggered by cool but not freezing nights and bright, sunny days, he said. Even the same plant can achieve very different color levels from one year to another based on such weather factors.

Not every kind of tree can produce a full red color even under the best conditions, though. Sugar maples are the most prominent example of those that do.

When most people ask what's the peak of the fall change, what they're really asking is when the sugar maples are going to change, Hedborn said.

New England is particularly known for its fall foliage because that's the heart of sugar maple country.

And while weather affects the level of color in the trees, the primary trigger for the change is the decreasing amount of daylight, Hedborn said. The prime time for the fall transition at Morton Arboretum is the second or third week of October, depending on weather conditions. White oaks change about a week after the sugar maples while sumacs are already changing now.

But because Morton Arboretum boasts a wide variety of tree species from different continents, the entire fall transitional period lasts from about the middle of September to early November.

For local forest preserves and other collections of largely native species, the whole color change probably begins and ends within a two-week time frame, Hedborn said.

Sue Dombro, naturalist at the Forest Preserve District of Cook County's Crabtree Nature Center near Barrington, said this period is usually the first half of October.

That's also the most visited time of year for the forest preserve district, and with good reason, she said.

"Besides a wide variety of trees, we have the full package of wildlife feeding on acorns, blooming prairie flowers and migrating birds that are only found at this time of year," Dombro said. "We have people call months ahead asking when they should take their vacations."

When leaves change in the Midwest

Peak foliage times vary, but

various sources agree on these general times.Late September* Northern tips of Wisconsin, Michigan, MinnesotaEarly October* Northern Wisconsin* Mid- and northeast MinnesotaMid-October* Northern two-thirds of Illinois, Indiana* Southern Wisconsin* Southern and northwest Minnesota* Southern Michigan* All of Iowa, Ohio* Northern MissouriLate October* Southern third of Illinois, Indiana* Southern Missouri* Western Kentucky, Tennessee* Northern Arkansas, northern tips of Mississippi, AlabamaEarly November* Mid-Arkansas, Mississippi, Alabama