The expression 'Indian summer' has been used for more than two centuries and is an informal expression given to a period of sunny, warm weather in autumn in the Northern Hemisphere. Typically this occurs in late October or early November, after the leaves have turned following an onset of frost but before the first snowfall. Since, untypically, we have already had several snows this season, I suppose we’re enjoying an unusual Indian summer, too. Still, we have had and are to continue to have warm, clear weather for the next several days.
In parts of the south-eastern United States, 'Indian summer' is colloquially used to describe the hottest times of the year, usually late July or August. But in the South, as elsewhere in the US, this period is more commonly known as the dog days, in reference to the position of Sirius, the 'Dog Star' and brightest star in the Northern Hemisphere, besides the sun.
The term 'Indian summer' is also used metaphorically to refer to a late blooming of something, often unexpectedly, or after it has lost relevance. This is comparable to the use of the term renaissance (French for "rebirth") in the sense of 'revival', but it carries the added connotation that the revival is temporary.
This piece of superfluous information was brought to you as a way to include the list of birds seen in my yard during the month of October:
White-throated Sparrow, White-winged Dove, Hermit Thrush, American Crow, Brewer's Blackbird, American Goldfinch, Lesser Goldfinch, Dark-eyed Junco, Pine Siskin, White-crowned Sparrow, Mountain Chickadee, Hairy Woodpecker, Black-capped Chickadee, White-breasted Nuthatch, Broad-tailed Hummingbird, Common Grackle, Turkey Vulture, American Robin, Red-winged Blackbird, European Starling, Northern Flicker - Red-shafted, Downy Woodpecker, Black-billed Magpie, Eurasian Collared-Dove, House Finch and House Sparrow