The earliest known written record of the term appears in a letter written by a French-American farmer named . In his book Letters from an American Farmer (1782), referencing a letter dated 1778, he wrote:
A darker theory suggests that the term stems from the warfare tactics on the frontier. Early settlers lived in fear of Native American raids. These raids were difficult to conduct once deep snows fell, as tracking was easier for settlers and movement was hindered. Consequently, the period of warm, dry weather before the deep snow was the last window of opportunity for raids. Settlers may have viewed this dangerous time as "Indian Summer." indian summer origins
By the late 18th and early 19th centuries, the phrase appeared regularly in American journals, such as those of Josiah Harmar (1790) and Ebenezer Denny (1794). 2. Theories of Origin The earliest known written record of the term