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 smoke irritates his eyes. Audubon suspects that the condition of the air was caused by Indians, firing the Prairies of the West. Audubon also mentions in many other places in his writings the reliance Native Americans had on fire. At no point does Audubon relate an Indian Summer to warm temperatures during the cold seasons. Because the warm weather is not a permanent gift, the connection has been made to the pejorative term Indian giver, which is also considered disrespectful or offensive. It is also suggested that it comes from historic native American legends, granted by the God or Life-Giver to various warriors or men, to allow them to survive after great misfortune, such as loss of crops. The term is considered by some to be disparaging of Native Americans; the American Meteorological Society recommends the equivalent term second summer. Weather historian William R. Deedler wrote that Indian Summer can be defined as any spell of warm, quiet, hazy weather that may occur in October or November, though he noted that he was surprised to read that Indian Summers have been given credit for warm spells as late as December and January. Deedler also noted that some writers only use Indian summer in reference to the weather in New England, while others have stated it happens over most of the United States, even along the Pacific coast. In literature and history, the term is sometimes used metaphorically. The title of Van Wyck Brooks' New England: Indian Summer suggests an era of inconsistency, infertility, and depleted capabilities, a period of seemingly robust strength that is only an imitation of an earlier season of actual strength. William Dean Howells' 1886 novel Indian Summer uses the term to mean a time when one may recover some of the happiness of youth. The main character, jilted as a young man, leads a solitary life until he rediscovers romance in early middle age. In British English, the term is used in the same way as in North America. In the UK, observers knew of the American usage from the mid-19th century onward, and The Indian Summer of a Forsyte is the metaphorical title of the 1918 second volume of The Forsyte Saga by John Galsworthy. However, early 20th-century climatologists Gordon Manley and Hubert Lamb used it only when referring to the American phenomenon, and the expression did not gain wide currency in Great Britain until the 1950s. In former times such a period was associated with the autumn feast days of St. Martin and Saint Luke. In the English translation of Boris Pasternak's Doctor Zhivago, the term is used to describe the unseasonably warm weather leading up to the October Revolution. Similar weather conditions, with local variations also exist.