Early Vermont Foliage Despite Record Hot Summer (They're Related)

A bit of fall foliage on my St. Albans, Vermont property this afternoon.
At the time I took this photo, the temperature was 91
degrees with a heat index of 99. 

It's gotten past 90 degrees in Vermont today, part of a record hot August, which followed a record hot July.

You'd think trees would want to stay green forever under these conditions, but anyone who's taken even a casual look around is seeing pockets of fall foliage already.

If anything there's more spots of color than usual for late August. That might not be as weird as you think. 

The heat, accompanied by dry conditions in many parts of the region, have stressed trees.

Stressed trees sometimes turn color early. Or the leaves just turn brown and drop off as the soil dries out, as you can see in some areas, like on the ledges on Interstate 89 around Colchester.

It's too soon to tell if this forebodes a weird or muted foliage season, but the danger is there. Very warm early autumns in particular, can screw up foliage.

That, of course is important to Vermont. For decades the Green Mountain State has had the reputation as one of the best places to go when those green mountains turn practically every color but green. Fall foliage has long been a necessary windfall - literally, actually if you consider the windblown, falling leaves of October. It's a big piece of what keeps Vermont's economy afloat.

More than three million tourists annually make a pilgrimage to Vermont each fall to basically watch leaves die.

The weather that sets up our fall foliage season has been weird in Vermont in recent years. Since it involves warmth, I suspect climate change is partly to blame, but I honestly don't have the scientific chops to prove that.

Last year tied for the second hottest September on record, topped by the latest heat wave on record in late September. The unusual heat extended into October, which became the hottest October on record. Dates as late as October 24 had near normal temperatures for July.

The foliage season was very late last year, and muted. In the warmer valleys, some color lasted into the first days of November, which is really weird. If this unusually warm weather continues through September and early October, we'll have another in a series of late foliage seasons.

It's gotten bizarre Tourists were told in the past to visit Vermont between very late September until Columbus Day to see the best foliage. In recent years, it has come later than that.

Last year, I was in a scenic, hilly section of Richmond, Vermont on October 8, an uncomfortably warm, humid afternoon reminiscent of a typical August dog day. The hills were almost entirely green at a time of year they should be just about at peak foliage.

While warm autumns make foliage seasons late, it doesn't necessarily doom their brilliance. September 2016 was tied with last year as the second hottest September on record and the foliage that year was pretty good. September, 2015 holds the record for the hottest September, yet the foliage that October was absolutely brilliant.

There's a lot going on that scientists don't yet understand about what triggers a good foliage season. I have to wonder, though, whether abrupt cooldowns in late September and early October save the season. In 2015, the final days of September and the first week in October were colder than normal. That might have saved that season. Last year, as mentioned, it was July in October and foliage was, meh.

A pretty orange falllen maple leaf in my
yard today, photographed while a heat
advisory was in effect. 

It does seem, though, that when unusual heat extends into October, we get some muted foliage.

There's no telling how Vermont's weather will play out this autumn. Early September looks hot, but beyond that is anybody's guess.

There are other factors that threaten to dull Vermont's fall foliage in future years. The most immediate threat is the emerald ash borer, which will soon kill pretty much all the white ash trees in Vermont, just as this terrible insect has done in other parts of the nation.

White ash adds beautiful golds and purples to the fall foliage palette, and those will sadly be gone in the coming years.

Looking further ahead, in coming decades some of the trees that create many of the most brilliant foliage, namely sugar maples, will tend to head north as the climate in Vermont gradually turns a little too hot for these trees.

They'll be replaced in part by oaks, which tend not to have as vibrant color as maples.

No matter how fall foliage season 2018 plays out - dull and late or vibrant and on time, there will be at least pockets of absolute beauty. And most likely more than just pockets.

Temperatures are in the 90s today, but those little patches of red sugar maple leaves out there now do feel like a little tiny breath of crisp autumn air.