Metro

Dave Epstein

Why New England’s peak fall foliage is a little later than usual

Craig F. Walker/Globe Staff/File
Fall colors enhanced the view of Easthampton, Mass., from Mount Tom State Reservation on October 18, 2016.

Around this time each year, New Englanders start asking questions about fall foliage. Everyone wants to know if the region’s foliage is going to be any good, and when to plan around peak viewing days and weekends.

The term “peak” just means that all the leaves have changed color, but if you wait for it, you’ll often miss some of the most vibrant leaves that change earlier. I find the best foliage viewing is when 50 to 80 percent of the leaves have turned.

While the leaves change color each year no matter what, some autumns are different in terms of how the colors appear. It’s a delicate balance between having enough moisture to keep the leaves healthy during the summer months, while also not having too much heat or cold heading through the fall. A hard freeze is horrible for foliage because it really damages the leaves. Windy conditions can also strip the leaves much earlier than they’d otherwise fall to the ground.

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The short-term problem with New England’s foliage this year is due the recent warmth. From the Boston area to Burlington, Vermont, to Portland, Maine, the past three weeks have been the warmest stretch in that timeframe since record-keeping began in about 1872. This comes on the heels of one of the warmest Septembers on record as well. Over the past month, we’ve had temperatures close to 80 degrees at some point nearly every weekend.

This was one of the warmest September on record across the Northeast data from the national climatic Data Center.
This was one of the warmest September on record across the Northeast data from the national climatic Data Center.

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Decreasing light is the main trigger for changing leaves, but cool nights and mild days are ideal for bringing on the color slowly and vibrantly. When temperatures are as warm as they’ve been in recent weeks, the rate of change slows down and can be muted a little bit, at least at the beginning of the season. The upside? The absolute worst weather for foliage is when it’s very cool and wet because fungus can really affect the quality of the leaves.

In the long run, though, I expect 2017 to be a great year for foliage viewing. While the warm weather has slowed things down a little bit, New Englanders will be treated to some very vibrant colors over the next few weeks. The pattern continues to be a warm one through Columbus Day weekend and even the weekend after, so you probably won’t need to wear a bulky sweater or sweatshirt while leaf-peeping anytime soon.

No matter what, you are going to find pockets of great color anytime between late September and late October somewhere in New England. Certain years are notably better than others, but Mother Nature always puts on a show.

Warmer than average temperatures are predicted through the middle of October.
NOAA
Warmer than average temperatures are predicted through the middle of October.