Cooler weather needed for cool fall color, experts say | Local News

As of yet, the deepest hues of autumn along Shoal Creek in Joplin aren’t in the trees.

Even as the season begins on the calendar, shades of dark brown, golden yellow and burnt orange are still easier to find in the Ozark clay caked on banks and bluffs than in the foliage growing from them.

In fact, with daytime temperatures stubbornly holding near 90 degrees, vibrant greens refusing to relinquish their hold on the leaves and perfectly comfortable birds continuing their songs, a passer-by could be forgiven for confusing today’s autumnal equinox with the vernal one six months ago.

While those who dread winter’s chill may welcome such conditions as a summer bonus, they’re not conducive to an aesthetically pleasing autumn, experts say.

“All we need now is warm, sunny days and cool nights to develop plants in their normal color pattern,” said Jon Skinner, a community forester with the Missouri Department of Conservation. “We’re wanting 75-in-the-day-and-45-at-night-type range, so if we don’t get a shift in temperatures soon, fall color just gets postponed further down the road. We may just suddenly go cold and everything turns brown.”

It’s not yet too late, Skinner said, but the next few weeks are critical for the development of fall color in Southwest Missouri. The Department of Conservation this past week began its annual practice of weekly reports of fall color from around the state, and Skinner said no one has seen any significant displays to this point.

Mid-September is typically when trees and other plants begin changing colors for the fall, the department’s website states, with roughly mid-October considered the peak for fall color. 

Any foliage currently changing color is likely not doing so because of the plant’s normal yearly cycle but because of some other stressor, such as insect damage or root issues, Skinner said. So the leaves may change color, but they will drop from the plants before fall’s peak. 

In healthy plants, the changing temperatures and other conditions lead to chemical changes, including the breakdown of chlorophyll, that cause the change in leaf color. During warmer months, substances like carotenoids and anthocyanins, which create orange, yellow and other colors, are masked by chlorophyll, which gives leaves their green color.

But the longer nights and lower temperatures cause chlorophyll production to slow before eventually stopping altogether, revealing the other chemicals’ colors.

Most years, the more vibrant fall color in Missouri is seen in the northern portion of the state, Skinner said. 

“We’re totally at the will of whatever the weather is going to be,” he said. “If the conditions don’t line up, you don’t get the color changes. We just live in the wrong part of the country to get dramatic, reliable fall color.”

Early fall forecasts  

Nighttime forecasts by neither The Weather Channel through Oct. 4 nor the National Weather Service through next week hold a low temperature below 50 degrees.

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