AMES – The Iowa Department of Natural Resources Forestry Bureau fall colors hotline began providing updates on September 19. The hotline number (515) 233-4110 is updated weekly with information on what colors are showing in which region.
The brightest displays of color occur with an early fall with bright sunny days and cool nights. These conditions develop red pigments. Cloudy days and warm nights will produce less brilliant colors because chlorophyll breaks down slowly and the red pigments are not formed quickly enough. Dry weather causes a greater buildup of sugars in the leaves, enhancing the production of the red pigments.
Windy, rainy weather causes many leaves to fall prematurely, lessening the intensity of the display. A killing frost will destroy the leaf cells and the coloration process will not function effectively.
Peak fall color occurs in northeast Iowa, on the average, on the weekend closest to October 10. Peak fall color occurs later in the more southern parts of the state, but it all depends on the weather.
The forestry bureau has fall color information on its website at http://www.iowadnr.gov/Environment/Forestry under “ForestryLinksPublications” that gives approximate best viewing times and what colors different trees produce.