Why is an Indian Summer So Called?

Answer 1

To understand the term "Indian Summer" you also need to understand the related term "Indian Giver". The history of the United States' dealings with the indigenous tribes of people in the US is not a vainglorious one. The US before, during and after the period known as the Indian Wars made multiple treaties with tribal leaders, many of which did not benefit the tribes, and later reneged or failed to enforce these treaties. The government also created the Bureau of Indian Affairs which was to provide Indian Reservations (created by the treaties) with the goods and necessities of life, which had been lost by the relocation of the tribes. Many of the BIA representatives were corrupt officials who would requisition goods for a reservation then divert those goods for sale at a profit to themselves. The tribes were often removed from their reservations when it was discovered that some sort of "need" was found on the particular site, and the tribes would be relocated again. This practice was derogatorily referred to as "Indian Giving" and the BIA and their agents were referred to as "Indian Givers." That is the practice of giving to the Indians then taking something back for one's own enrichment.

"Indian Summer", which often comes in the winter season, is called such because it's a warm period, which might signal the coming of summer, but it is followed by another cold spell, or return to the normal winter weather. Essentially, the weather is being called an "Indian Giver" by giving then taking back warm weather. Hence the term.

Answer 2

It's been around for more than 300 years. First known usage was by a writer in 1778, John Hector St John Crevecoeur. There are several theories as to it's etymology,

First, similar to Indian giver, someone taking back presents given, in other words; a false summer.

Second, some believe the term may have originated from raids on European colonies which usually ended late autumn because of snow, hence summer-like conditions in late fall was an "Indian Summer".

Third, some believe it originated as a term for harvest time for the indians themselves.

Fourth, In colonial England and New york, Indian Summer referred only to a January thaw, when tracking the indians back to their camps became more difficult.