Indian Summer. An Indian summer is a period of unseasonably warm, dry weather that sometimes occurs in autumn in temperate regions of the northern hemisphere.
Several references describe a true Indian summer as not occurring until after the first frost, or more specifically the first killing frost. The late 19th-century lexicographer Albert Matthews made an exhaustive search of early American literature in an attempt to discover who coined the expression.
The earliest reference he found dated to 1851. He also found the phrase in a letter written in England in 1778, but discounted that as a coincidental use of the phrase.
Later research showed that the earliest known reference to Indian summer in its current sense occurs in an essay written in the United States circa 1778 by J. Hector St. John de Crevecoeur. The letter was first published in French.
The essay remained unavailable in the United States until the 1920s. Although the exact origins of the term are uncertain, it was perhaps so-called because it was first noted in regions inhabited by Native Americans, or because the natives first described it to Europeans, or it had been based on the warm and hazy conditions in autumn when Native Americans hunted. John James Audubon wrote about The Indian Summer that extraordinary Phenomenon of North America in his journal on November 20, 1820. He mentions the constant Smoky atmosphere and how the s