Fall foliage in Illinois

Illinois runs north to south over roughly two weeks. The sandstone canyons at Starved Rock lead in the third week of October, and the change travels down the river bluffs to the Shawnee National Forest, where Garden of the Gods, Giant City and Ferne Clyffe peak around the turn of the month; the southern tip around Little Grand Canyon and Millstone Bluff closes in early November. Maple and hickory carry the north. Oaks, sweetgum and black gum give the Shawnee a longer, warmer finish.

Color somewhere in the state: October and November
Trees: maple, hickory, oak, sweetgum and black gum
Region: Great Lakes & Midwest

Those are the months when color is present somewhere in Illinois, from its highest ground to its lowest. Any one location changes over a much shorter period than that.

Why the timing shifts from year to year

Shortening days start the process, so most places in Illinois change at close to their usual time each year. Within the state, elevation and latitude account for most of the difference: higher and more northern ground generally changes first, and lower, sheltered ground last. Weather has more effect on how strong the color is than on when it appears. Cool nights and sunny days favor the reds, a dry summer mutes them, and a hard freeze or a windstorm can strip a slope in a day. What determines the timing goes through this in detail.

Nearby states

Fall color does not follow state lines. Illinois borders:

Timing for a specific place

This page describes a whole state, which is about as precise as a season can be described in words. Conditions at one overlook on one weekend are a narrower question, and that is the one Fallcast answers: an expected period of color for a specific location, with a confidence attached, updated through the season as the trees change. It is coming to iPhone this fall.

Questions, or somewhere in Illinois you would like covered? Write to fallcastapp@gmail.com.