Super El Niño Shifts Ontario's Fall Foliage Timeline

A climate pattern dubbed the “Super El Niđo” is disrupting global weather and impacting the timing of Ontario’s autumn colors, according to reporting from Global News Toronto.

David Phillips, a climatologist with Environment and Climate Change Canada, states that the typical window for fall foliage, which usually runs from mid-September to late October, has been pushed back by several weeks this season. This shift is attributed to the warmer-than-normal fall weather brought on by the phenomenon, which scientists expect to be the strongest El Niđo on record.

Susan Dudley, a biology professor at McMaster University in Hamilton, explains that cooler nights typically trigger the change in leaf color. Because of the warmer weather, the onset of these colors may be delayed, or the period during which the colors change may be extended. Dudley notes that while the foliage might be “slightly duller” because trees require fewer anthocyanins—the pigments that act as a form of “sunscreen”—the trees have not been as stressed as they were during the previous summer.

Phillips notes that while rainfall varied across the province, trees generally received sufficient precipitation. He also highlights that El Niđo has significantly reduced Atlantic hurricanes this year, which often bring the winds and heavy rain that cause leaves to brown or drop prematurely.

Despite the delay, the seasonal progression continues from the north toward the Greater Toronto Area. Algonquin Provincial Park has already reported that red and sugar maples are displaying peak foliage at the canopy level.