Many people tell me that their favorite time of year is Autumn. The lingering warmth of summer combined with the cooler mornings from longer nights makes it a great time of year to enjoy Idaho's beautiful outdoors.
That very combination that gets many people more active is what causes our trees to slow down and get ready for a long winter. Chlorophyll present in the leaves during the summer give them their green color. The shortening of the daylight hours signals the trees to stop the production of chlorophyll causing the the green to disappear and the colors to paint the countryside with bright yellows and reds.
Leaves have some of the colors already but when the chlorophyll production stops, sunlight causes the remaining chlorophyll in leaves to turn different colors.
Eventually the leaves fall to the ground as the trees go dormant for the winter. This map shows Idaho hitting peak in mid October. While this is true for the valleys, peak hits at the end of September for many of the Aspen in the higher elevations.


















