Generally, peak season is between the first and third week of October, before the leaves change completely. Of course, weather and outside circumstances can play a role in the exact timing each year.
In 2021, foliage peaked in most parts of New Hampshire the week of Columbus Day. However, if you plan to come during that weekend, expect heavy traffic and large crowds.
The Kancamagus Highway is definitely one of the best scenic routes to take in the fall colors.
Use the Fall foliage tracker!
New Hampshire’s website has a perfect tool for tracking fall color in different regions each week. Each week it is updated with current conditions, so you know which areas are about to peak and which still have time to change. -> Fall foliage tracker