Fall colors may be muted and delayed this year thanks to warmer weather

Science

(WVNS) — As we get farther into the fall season, have you noticed the fall foliage is not as vibrant this year? You aren’t alone, and there may be a meteorological reason for the muted colors in this year’s fall foliage.

Aside from muted and dull colors, our timing is a bit off this year with many trees still holding on to their green leaves. In past year’s our peaks have been about a week earlier than we are experiencing this year. This too is thanks to our unique weather pattern this year.

Fall colors depend greatly on environmental cues trees receive all growing season long. The amount of sunshine vs. clouds, the amount of rain vs. dry, even down to the timing within the growing season trees get these cues. For 2021, we’ve experienced drought conditions for much of the summer season. This dry spell gave some trees a signal to abandon their leaves sooner. It wasn’t until later into the summer and beginning of fall that we began to see rain amounts that helped alleviate drought conditions across the region. For some of our trees and small bushes, the dry conditions already took their toll. Many of our small trees, bushes, and shrubs started turning colors well before we typically see the transition.

While a majority of our forests remain mostly green now, the extra rainfall we received and warmer days helped keep trees from making the fall change. Along with moisture cues, temperature cues play a big part in when a tree will change colors. This is often species-specific. A cold snap in late September did help jumpstart our fall foliage but it didn’t last. This cold spell was followed by repeated cloudy days with multiple rounds of rain and was rather short-lived. A warm-up in October is responsible for keeping us well above average at a typical time of the year we start to see widespread and vibrant colors. Not for 2021, however. The warmer days and warm nights have accelerated sugar breakdown in our trees which is responsible for the fall colors. This lead to more trees with muted colors.

In years we’ve had cooler than average October’s, fall colors have been viewed as some of the best around. For our region, the fall colors of 2014 come to mind thanks to a few cold snaps that year.

This is also the reason the dates on our predicted peak fall colors map and our average first freeze map line up so well. It is the cooler nights that help trigger the widespread fall colors for our region.

In order to have a vibrant fall change over, most trees need a moist growing season early (spring and early summer) with a dry end to the growing season (late summer into early fall) followed by sunny and warm days with cool and crisp fall nights. Something this year’s growing season did not provide.

However, with a big cool down expected towards the end of this week Saturday, October 16, and Sunday, October 17, which is expected to give us an extended period below average, our stubborn green trees will finally get the cue to begin shutting down their leaves leading to more fall colors. While still beautiful in their own rights, the damage from the summer drought and long above-average warm-up for October, the colors of 2021 won’t be as vibrant or as long-lasting as years past.

With differing species-specific meteorological cues, we will still have the yellows, oranges, and reds we’ve come to love about the fall season. As you are out and about enjoying the 2021 fall foliage, here’s a graphic to help you in identifying which trees you are looking at. This is possible because each species changes colors in unique ways which can be used to identify each tree.

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