Many of us envy places where fall brings a brilliant display of changing leaves. The vibrant reds, oranges, and yellows signal the shift in seasons. But why is it so rare for us to experience such beautiful fall colors?
Chief Meteorologist Anthony Yanez explains the science behind why our leaves rarely put on that stunning display.
Have you ever wondered why our leaves in the fall don’t look like this? Let’s start with the basics. Chlorophyll is the green pigment in leaves that traps sunlight, water, and carbon dioxide which plants and trees use for food in the growing season.
Chlorophyll is why leaves are green. But as our season changes to fall, and the sun angle lowers, the intensity of sunlight decreases.
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When this occurs, cells form at the base of the leaf and stop carrying fluids to the leaf.
At this point, photosynthesis stops. But before we get here it’s important to understand that during the growing season, the colors green, yellow, and orange are already present in the leaf. But green is the dominant color due to chlorophyll production.
When this stops, yellows, and oranges are revealed. Reds and purples come out with seasonable weather.
That really is the key phrase. Because without a distinct change in seasons, leaves will go from green to brown. If temperatures are too warm, fall colors are muted. This is our biggest issue. We were in the 90s last week and this week. You can sometimes describe our fall season as going from hot, to not as hot.
But there have been years with early strong cold fronts. This cooler weather with more sunshine and chilly nights will make our leaves more vibrant.
Precipitation is a big factor too. When the weather is dry, like ours has been since August... fall colors are muted and delayed. I have friends in Michigan who told me their colors aren’t good this year because of their dry weather.
But with just the right amount of rain at the end of summer and early fall, the change in leaf color can be fantastic!
I think the map really shows our issue with warm fall temperatures. This is the average fall foliage peak. The range is late September to late November looking at the years from 1991 to 2020. This data is from Evan Fisher at Explore Fall.
When I zoom into Houston we get… Insufficient data from The Woodlands to the coast. But our best chance to get some color change is in late November in cities like Conroe, Huntsville, and Livingston.
And the big reveal! Our forecast for this year in all of southeast Texas… Low color.
