Everyone wants to know when will be the best time to view autumn’s big show, but leaf color predictions can be quite tricky because of the interaction of environmental factors that influence leaf color. Most of the factors are related to weather conditions prior to and during the leaf color change. Specific weather conditions are difficult to forecast 4 to 6 weeks in advance. Past weather conditions indicate trends for what can be expected. Changing leaf color is triggered by the shorter days of sunlight, which is called the photoperiod. This is constant from year to year, and then influenced by temperature and moisture. Broadly, these weather condition generally yield specific results:
- Warm, dry weather with extended droughts or moisture deficits: Yields color that is not as vibrant, is short lived (a week or so) and the timing can be delayed a week or more.
- Adequate moisture: Yields a longer period of leaf color.
- Sunny days vs. overcast days: Sunny days create more vibrant leaf color. Leaf color is less vibrant (more
dull) with several rainy or overcast days in a row when leaves are turning color.
- Cool nights and warm days: Cool nights with temperatures in the 40s and low 50s (but not freezing) with daytime highs in the 60s and 70s tend to retain leaf color longer, and the colors are more pronounced, especially if the days are sunny.
- Freezing overnight temperatures and early frost: Show’s over. Leaves will turn brown and die.
The color of leaves changes first at the higher elevations where it is cooler, then progresses to the valleys at the lower elevations. Color in the mountains usually begins during the second week of October and advances to the valleys and the Coastal Plain of west Tennessee by the end of October and even lasting into the first two weeks of November. Thus, leaf color can be seen at various dates depending on your location.
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