Rain: A damper on foliage?

For those keeping track of the incredible record run of rain, here is where stand:

--The total for September, 10.08, is No. 3 in the period of record dating to 1872.

--With a quarter of the year remaining, the combined August-September precipitation total, 29.39, is better than the 12-month totals for the years 1922 and 1965.

--With a quarter of the year remaining, the precipitation total since Jan. 1, 52.19, already makes this the fifth-wettest year on record.

The rains combined with the late-September warmth -- it hasn't gone below 60 since the 20th -- may conspire against the foliage season, in the view of Penn State foliage expert Marc Abrams.

Abrams has been watching the leaves change for over two decades with a scientific interest, and he's not liking what he's seeing right now.

"It's hard for me to be optimistic," he said this morning. In the universe of foliage, the changing light rules. But embedded in that sun angle-day length signal is the variable of day-to-day weather.

The peak foliage period can vary from 4 to 10 days in an given year, said Abrams, depending on the weather.

The most-vibrant colors are produced by cool nights, prefereably in the 30s, so the trees more or less take the hint that the seasons are changing.

That hasn't been the case so far, obviously, and all this tree-nourishing rain could present another issue.

Historically, says Abrams, dry conditions promote the best color.

You may recall that once upon a time the region did experience dry conditions. A drought watch was hoisted for the entire region back on Aug. 5.

That summer drought stress could be a wild-card in affecting peak color, said Anthony Aiello, horticulturalist at the Morris Arboretum.  

"Mother nature," said Abrams, "has pretty much thrown everything at the trees."

But both Abrams and Aiello note that the foliage season around here is rarely a complete bust, and remember that not many places in the world get a foliage show as dramatic as our's.