How to Read the Foliage

We're on the last few miles now, so let me leave you with the thing this road is most famous for, and how it actually works — because the science of it is better than the postcard.

All summer a leaf is packed with chlorophyll, which is green and which masks everything else. As the nights draw in, the tree reads the shortening DAY — not the temperature, the day length — and begins closing the leaf down, sealing it off at the stem. The chlorophyll breaks apart, the green drains away, and what's revealed underneath are the pigments that were there all along: carotenoids, giving you the yellows and oranges of birch and beech and aspen.

But the reds are different, and this is the good part. The scarlet of a sugar maple isn't a pigment that was hiding — the tree MAKES it, fresh, in autumn, out of sugars trapped in the dying leaf. Which means the red depends on the weather in a way the yellow doesn't. You want warm sunny days to build sugar, and cool nights just above freezing to trap it. Get that combination and the maples go incandescent. Get a warm wet muggy September and the same trees go a disappointing brown.

So the reds are a genuine, year-by-year accident of weather — which is why locals talk about a good year and a bad year like they're talking about wine.

Peak on the Kancamagus usually lands somewhere in the first half of October, higher elevations first. But go any week from late September into mid-October and this road will give you something. And go on a weekday, at dawn, if you possibly can.