Predicting Ohio's fall colors not an exact science

By the Ohio Department of Natural Resources

Like the forecasts for the weather conditions that influence the changing autumn leaves, predictions regarding the quality of Ohio’s fall color, while based on science, are not infallible.

Predictions about the brilliance and longevity of Ohio’s fall foliage are often based on variables such as sunlight, temperature, rainfall and wind. Bright sunny September days and cool nights tend to make red, orange and bronze leaves more vivid. Early frosts often cause trees to prematurely build an abscission layer, a barrier that builds up between the leaves and branches and prevents carbohydrates and water from passing in and out of leaves, thus turning leaves “ahead of schedule.” Dry conditions can cause a delay in leaf color change and windstorms can quickly bring leaves down, ending Ohio’s fall foliage season abruptly.

The seasonal leaf change phenomenon takes place every year and is easy to predict. Each October, leaves throughout Ohio turn colors and drop from trees. The transformation, which occurs earlier in northern Ohio than in the southern part of the state, is caused by a decreasing amount of daylight as the season changes. As a result, the formation of the abscission layer causes green chlorophyll to break down so that colors like gold, yellow, brown and orange show through – especially in hickory, birch and beech trees.

At the same time, the leaves of many “sugary” trees such as maples, dogwoods and sweetgums undergo a chemical change triggered by the cool nights and sunny days that are characteristic of mid-to-late September. The chemical change results in deep russet, purple and bronze shades.

Predicting how vivid and durable fall color will be is not an exact science, but Ohioans can be assured that it will arrive and that it will exhibit the rich variety of palettes and textures.

Visit www.dnr.state.oh.us/tabid/9584/Default.aspx to find out about fall foliage viewing opportunities and exciting autumn activities at Ohio state parks, forests, preserves and natural areas.