OTTUMWA — The Iowa Department of Natural Resources thinks southeast Iowa is about a week away from this year’s peak leaf color.
Fall temperatures took a plunge late last week. The change from previously warm, humid air has helped spur the seasonal change, with northeast Iowa beginning to show significant color. That’s close to two weeks behind normal. Trees in the northern third of the state typically peak in the last week of September through the second week in October.
The outlook suggests southeast Iowa will seek its peak on the days around Oct. 20, more or less on schedule. Predicting peak color isn’t exact, though. A strong storm can cut the season short.
And not all trees change at the same time. Monday’s report from the IDNR said trees like walnuts and cottonwoods are starting to turn, as are sumac and dogwood. Maples are still “mostly green.”
The changing colors of the leaves is caused by the slowed production of chlorophyll, which keeps the leaves green, and the emergence of other pigments in the leaf. The IDNR said sap builds up in the leaves during this process, and the sap’s acidity plays an important role in determining the final color of the leaf.
Iowa residents know they can get a good show if everything comes together, and it looks like this could be one of those years for the southeastern part of the state. There are no significant storms in the National Weather Service forecast for the upcoming week. Temperatures will be chilly overnight, with daytime highs in the 50s and 60s.
So, dress for the weather if you go out to look at the leaves. And keep your fingers crossed. This could be a nice year.