Indian summer.

I've always wondered.
Indian Summer
Definition: A period of warm weather following a cold spell or a hard frost, Indian summer can occur between St. Martin’s Day (November 11) and November 20. Although there are differing dates for its occurrence, for more than 200 years the Almanac has adhered to the saying "If All Saints’ brings out winter, St. Martin’s brings out Indian summer." As for the origin of the term, some say it comes from the early Native Americans, who believed that the condition was caused by a warm wind sent from the court of their southwestern god, Cautantowwit.

Update: I love the Farmers' Almanac. It tells me that tonight, Thursday night, is the Full Beaver Moon or Frost Moon, a sign of freezing weather coming up. And that tomorrow (the 15th) is the birthday of composer Aaron Copland.
And I get this little timely poem:

No shade, no shine, no butterflies,
no bees
No fruit, no flowers, no leaves,
no birds! -- No-vember!
—Thomas Hood (1799-1845)