
The expression "Indian Summer" is often used for an unusually beautiful late summer. In the south of the USA it is considered the hottest period of the year (July-August). However, the real Indian Summer takes place in the northeastern United States, in the New England region.
In October, cold polar air from Canada is struggling to expel the remaining warm air in the northeastern states. This phenomenon creates a high pressure area. The heated air will remain, as it were lying on the ground, covered with a layer of cold air. The first day of the Indian Summer is usually pretty cold,

but the subsequent days are getting warmer, even over 77°F / 25°C . The first nights of frost are the signal for the trees to stop the food supply to their leaves. This also stops the production of green chlorophyll pigments, and the color of the leaves turn red, brown and yellow. This process is enhanced by the relatively high temperature, and it gives the Indian Summer its characteristic and spectacular sight.
Where does the term `Indian Summer´ comes from? There are a few theories:
- The first European settlers welcomed the colder autumn period as the time when they did not have to fear more attacks from the Indians. When they left their settlements unarmed, and quite suddenly a warm period started, the Indians agreed to a final attack on the settlers.
- The period during which the Indians harvested their corn and pumpkins.
- The Algonquian tribe believed that their southwestern god Cautanowwit blew warm air from his court toward the northeast.
The precise time and the strength of the Indian Summer difficult to predict. Nature is capricious - it's different every year.
USA Bike Tours offers a few foliage (autumn) bike tours in New England, focused on the wonderful Indian Summer.
Maine Foliage Ride
Fall Foliage Ride
Autumn in the Berkshires