As the heat of summer fades into the cool weather of fall, trees and shrubs around the Show-Me State transform from leaves of green to a fall-foliage color palette of golds, reds, oranges, and purples.

Leaves turn colors when two things happen. First, sugars produced by photosynthesis are trapped inside leaves by chilly - but not freezing - autumn nights. Those sugars are the building blocks for red, yellow, orange, and purple pigments. Cool nights simultaneously cause the breakdown of green pigments, allowing these other colors to show through.

Missouri’s fall color starts in late September and usually peaks in mid-October. This progression of color change starts earliest in northern Missouri and moves southward across the state. Normally by late October, colors are fading and leaves are beginning to drop from trees. Generally, color change is predictable, but can vary year to year, depending on weather.

According to Missouri Department of Conservation Forestry Field Program Supervisor Nick Kuhn, autumn weather will be the biggest factor affecting this year’s fall color.

“It has been a decent year for most trees,” says Kuhn. “Sufficient rain, moderate temperatures, no serious insect problems, or weather events means trees are happy and doing OK. The fall weather will be the major factor in showing us those wonderful hidden colors in all trees. Watch for sunny days and cool nights with no frost to know when to start looking for color changes. I predict that across the state, the best week for fall color change will be the last week of October.”

The Conservation Department provides weekly fall-color reports and has developed a free mobile app to help Missourians discover fall color around the Show-Me State. The report combines information from foresters around the state in weekly online updates at mdc.mo.gov/node/4548 from late September through November.

The Conservation Department’s free MO Fall Color application is available for smart phones and other mobile devices. It provides up-to-the-minute fall-color scenes from around the state, complete with GPS navigation information. The app also provides weekly fall-color reports for various areas of the state. Users can even add their own fall-color photos and share them with Facebook friends and others. The MO Fall Color app is active during fall-color changes beginning in September through November. Download MO Fall Color for Android and Apple devices at http://mdc.mo.gov/node/19321