Photo: Mimi Ditchie Photography / Moment / Getty Images
(Des Moines, IA) -- It’s officially fall, but central Iowa still has a few more weeks before trees begin their colorful transformation.
Today, September 22, marks the autumn equinox, the first day of astronomical autumn in the Northern Hemisphere, signaling cooler weather and shorter days ahead. On this day, the sun is directly over the equator, resulting in nearly equal hours of daylight and darkness.
“The sooner it gets to those cool nights, that’s going to trigger a lot of these hardwood tree species to go into their dormancy stages,” said Mark Runkel with the Iowa Department of Natural Resources.
Runkel says the first trees to change will be black walnuts, hackberries, and silver maples.
“It’s unseasonably warm, but because we’ve had a warm spell, then a cool spell, and now another warm spell, combined with all the rain we’ve had this summer, that’s probably going to lead to really good fall colors,” he said.
In central Iowa, trees are expected to start changing around mid-October, once temperatures drop enough to trigger dormancy. According to the Iowa DNR, fall colors in central Iowa typically peak between October 21 and 25. In northern Iowa, colors tend to peak earlier, around mid-October.
This year, Runkel says northern Iowa could see trees start changing as early as the last week of September.
“If you really want a good indicator that fall is coming, look at your black walnut tree,” he said.