ROANOKE, Va. (WDBJ) - If you live in the Virginias for any length of time, you know there’s never a terrible year for fall foliage. However, some years are much better than others when it comes to vibrant colors. Fall 2019 was lackluster due to a hot summer that lingered into the fall. The 2018 fall season featured just the opposite -- two tropical systems that kept us dark and rainy. This year, however, “could end up being one of the best fall seasons in years," according to tree expert Dr. John Seiler, Professor of Tree Biology at Virginia Tech.
The fact the trees change colors each autumn is a given. The big question is, just how vibrant will they be and when will the changes occur?
In the fall, because of changes in the length of daylight and changes in temperature, the leaves stop their food-making process. The chlorophyll breaks down, the green color disappears, and the yellow to orange colors become visible and give the leaves part their gorgeous colors. This keeps going until all the leaves have changed colors, or the tree drops the leaves as it goes into dormancy.
There are several ingredients that go into the color transformation each autumn. Some are related to sunlight, and others the weather.
- Amount of daylight
- Naturally occurring cooler temperatures in the fall, especially at night can accelerate changes
- Weather extremes (too much rain, drought)
- Health of trees
WEATHER IMPACTS COLOR INTENSITY
Even during the worst leaf-peeping seasons, the leaves will still change their colors. It’s part of nature’s cycle. However, temperatures, light, and even rainfall have a major influence on the degree, color intensity, and the duration of the fall colors.
COOL, BUT NOT FROSTY: According to tree experts, low temperatures above freezing will favor anthocyanin formation producing bright reds in maples.
EARLY FROST: An early frost will weaken the brilliant red colors and often cause the leaves to fall prematurely
AMPLE SUNSHINE: The sunny days and often mean cool nights in the fall which is ideal for colorful changes
STRONG WIND & HEAVY RAIN: This is equally as bad as a frost since wind can often blow the leaves off prematurely and too much rain during the color changes can lead to dull colors.
Seiler says to hope for long stretches of cool, dry weather leading into the middle of October. This will accelerate the changes and lead to more vibrant colors.
PROJECTED PEAK DATES
While even the smallest, last-minute weather conditions can impact the color changes, here’s a look at when to expect the best fall colors according to tree experts at Virginia Tech.
WHY DO SOME TREES CHANGE LATER THAN OTHERS?
Some trees are known to change earlier in the season, while some wait until it’s almost winter. “In some tree species, it’s just genetics," says Seiler. A good example is black gum. It turns a gorgeous orange and red much earlier in the season than the others.
One reason why a tree drops its leaves later could be due to soil quality, health of the tree, or even the fact that it’s in a more shaded location. “More often than not, it’s the tree species, says Seiler.”
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