Why do the leaves change?
-Weather-
Introduction
As mentioned in the introduction, temperature plays
an important role in the foliage process. In addition to temperature,
two other meteorological parameters also have an impact on foliage,
precipitation and wind.
Temperature
Ideally, the best foliage occurs when autumn days are mild and the
evenings are cool and crisp, but not below freezing. However, if
daytime temperatures are too warm for a relatively long period of
time in the fall, the colors may be less intense. The foliage season
may also last one to two weeks longer. Frost tends to inhibit the
production of anthocyanin, a pigment producing various shades of
red. This is why having temperatures above freezing is advantageous.
The temperature during the Spring can also have an impact on the
fall foliage. ;A late Spring may delay the color change by a week
or two.
Precipitation
Annual precipitation, which provides moisture for soil and plant
life, also plays a role in the foliage. A late spring, which delays
the release of moisture through snow melt, may push back the color
change by a nearly a week, sometimes longer in extreme cases. Severe
drought often causes the leaves of young and distressed trees to
turn brown and drop early.
Wind
The third parameter, wind, has a rather obvious impact on the fall
foliage. Very windy conditions, like those observed during and after
storms, cause the leaves to drop, sometimes before full color has
been reached. Therefore, calm winds are most favored during the
foliage season.
Ideal Foliage
Weather As you can see, the weather has a strong impact on the foliage
season. It can dictate the timing of the foliage, the intensity
and type of colors seen, and the duration of time the leaves will
remain on the tree.
Ideal foliage is produced by a warm and wet spring, typical summer
conditions, and mild, sunny autumn days with cool evenings (which
stay above 32° Fahrenheit).
Other "About Foliage" Sections
A Guide to the leaves
How to preserve leaves |
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