ALPENA, Mich. — Color changes on the trees in Northeast Michigan are reaching their peak. Forest Resource scientist Bert Cregg explained one of the key factors that will make vibrant colors happen more quickly. “As the nights in particular get colder, that’s one of the signals that’s going to prompt the tree to start breaking down chlorophyll, the green that we see, and making visible some of the other pigments, other colors.”
Following a summer that set a tie for record seasonal heat, temperatures returned to values closer to the long-term normals in September. It’s typical to have low temperatures falling to the middle or lower 30s beginning in mid-September. Cregg said, “Once you start having some nights that are freezing, or close to freezing, that’s certainly going to set things into motion.”
Alpena had three days in a row when temperatures dropped to the lower 30s or upper 20s – on September 18, 19 and 20. When it comes to moisture, professor Cregg said there’s more to consider than just total monthly rainfall. “When we look at some of the rainfall totals or averages, it can sometimes be misleading because you can have a few big rains and dry periods in between.”
Professor Cregg added that a couple weeks without substantial rainfall can speed up the changes from green leaves to vibrant colors. From September 11 to 25, Alpena had less than one-tenth of an inch of rain.
With colder temperatures on the horizon, heading toward the end of October, now is the time to get out and enjoy the colorful fall scenes.