Fall Colors - Sept. 21, 2007

Get your cameras ready, we are just a few weeks away from the start of the fall foliage season. While this year’s color may not be the very best we have seen, the wet year has caused trees to put on a full and thick coat of foliage, increasing the view. Autumn’s show is nature’s calendar. A way to remind us the hot summer weather is ending and cooler autumn temperatures are ahead. The two biggest factors that determine when leaves begin to show off are temperature and precipitation. Leaves help produce food needed for tree’s growth. The chlorophyll in leaves absorbs light and helps convert carbon dioxide to starch and sugar. But as the temperatures begin to cool, the leaves stop producing food and the chlorophyll breaks down, allowing the red and yellow pigments already present, to appear. As the daylight hours get shorter and the night longer we often have sunny and warm afternoons and very cool nights. The sugar that was produced in the leaves during the daylight hours struggles to make it out of the leaves when the nights get cold. The sugar that remains in the leaves changes to a reddish colored pigment. When the leaves change depends a lot on how soon our night’s temperatures get cool. Ideally, you want lows in the mid to upper 40s for several weeks, and go below freezing too soon. We begin to see our peak colors, usually by mid to late October when our afternoon highs in the 60s and lows near 45. Most areas have had a wet year, and the fall temperature outlook is for warmer than normal temperatures. You do not have to fly to New England to do leaf watching. Reds, yellows, oranges, and scarlet leaves will be coming to a tree near you very soon. Slow down, budget some time, to check out nature’s show. If you have a weather question, send it to: askdan@kjhr.com