Predictions

About this time, each summer, Google Alerts sends links to articles containing “Fall Color.”

It’s fascinating to read these Google Alerts and learn whether fall color is being predicted to be early, late or about normal, and why prognosticators think so.

Most fall color forecasters are meteorologists who base their predictions on measured precipitation and temperatures. So far so good, but then they get out of their lane and guess what effect too little or too much rain, too warm or too cold autumn days might have on forthcoming foliage.

From years of observation, I’ve found that more or less precipitation tends to lengthen or shorten the display of fall color. It does not make it appear earlier or later. With more water, deciduous leaves last longer on branches. With less water, they dry up and fall off sooner.

It’s not water or lack of it that causes color change, it’s the seasonal change in temperature and light. As days shorten due to the Earth’s rotation, leaves get less light and nights become colder.

At first, the change is imperceptible, but then, gradually, the production of green chlorophyll slows and underlying yellows, oranges and reds emerge. Temperature intensifies or dulls fall color, but it does not make it appear earlier or later. Warm days and cold nights stimulate the most vibrant displays.

So, when is fall color predicted to appear?

• Connecticut – one source says early, another says late, both agree that drought is the cause
• Massachusetts – late
• New England – Yankee magazine estimates it will peak in any time from Oct. 5 – 22 or Oct. 12 – 28 or even as late as early November.
• Wyoming – normal (early to mid Sept., continuing to mid Oct.)
• Ohio – late
• Minnesota – early

As for California? It’s too early to say.