The Chicago area will get a taste of fall weather in the coming days, and many people will likely be preparing for the start of the new season and everything that comes with it: changing leaves, pumpkin spice, sweater weather and more.
Even though some leaves are already showing signs of changing, when can you expect the height of fall foliage?
“We’ve still got a little ways to go,” said Kevin Jeanes, meteorologist with NBC 5’s Storm Team.
Here’s a timeline and what to look for weather-wise to see how vibrant fall colors could be:
End of September
According to Jeanes, leaves will begin changing color in northern Wisconsin around September 15.
“The colors are starting to change at least further north in Wisconsin as we get into the last week and a half of September,” he said. “The colors are changing there.”
Mid-October
Once October rolls around, colors should start to change across much of the Midwest.
“This is really the month we’re talking about when the leaves start changing color here,” Jeanes said.
By October 15, notable changes are expected in the Chicago area.
According to Illinois’ “Fall Color Trip Planner,” the estimated peak times for leaves from Galena, through the Chicago area and up to Starved Rock are the second week of October.
The Farmers Almanac predicts that peak color for northern Illinois will be somewhere between October 5 and 21.
End of October
Peak colors typically persist in the Chicago area and Illinois through late October.
“The last week or week and a half of October,” Jeanes said.
For central Illinois, this is the estimated rush hour, according to Enjoy Illinois.
November
By the time November arrives, the fall leaves are expected to be past their peak.
“Once we get to November, that’s when we’re past peak and the leaves start falling,” Jeanes said.
What could change this timing?
Certain factors can change the color of the leaves and their lifespan.
Already, popular trees in landscaped areas are starting to show the first hints of color, Christy Rollinson, a forest ecologist at the Morton Arboretum, told Telemundo Chicago.
Trees typically start to change as the days get colder and nighttime temperatures get consistently quite cold — down to the 40s, 30s or even lower, Rollinson explained.
While an early peak of fall colors is not expected, Rollinson noted the possibilities.
“Things can change very quickly as we move into September and October,” she said. “What happens day to day has a strong influence on the process of how trees change color and prepare for winter.”
The past month and much of the growing season have been fairly mild for trees, although the extreme heat in late August may have caused increased stress, she said. However, that may not have much impact.
Jeanes said that overall, a hot, dry summer can dull the brightness of leaf colors, but the Chicago area had a relatively average summer when it came to rain, meaning the region should see a moderate color change this season.
Although periods of extreme heat and cold temperatures are expected across the region in the coming days, this may not have as much of an impact as one might expect.
Morton Arboretum and its research partners have found that trees actually respond to extreme weather over longer periods of time (several weeks or more) compared to heat waves or short-term droughts.
“Trees are really well equipped to hold up and play for the long haul,” Rollinson said.
Why do tree leaves change color?
While it may seem like peak colors won’t appear for several weeks, you may be wondering what causes trees to change color in the first place — or what causes these vibrant hues.
According to an article from the Smithsonian Institute, trees whose leaves change color are green most of the year because of the chlorophyll they use to absorb energy from sunlight during photosynthesis.
But as temperatures drop and days get shorter, trees receive less direct sunlight and the chlorophyll in the leaves breaks down.
“The speed and extent of leaf transformation varies across the globe,” the article explains. “The best colors are produced when the weather is dry, sunny, and cool. Cloudy, humid, or warm locations will not experience the same degree of color change.”
