Indian Summer: What, Why, and When

In the fall, it seems that almost any warm day is referred to by most people as “Indian summer.”

And, while their error is certainly not of the world-shaking variety, they are, for the most part, in error. 

Here are criteria for an Indian summer:

  • As well as being warm, the atmosphere during Indian summer is hazy or smoky, there is no wind, the barometer is standing high, and the nights are clear and chilly.
  • A moving, cool, shallow polar air mass is converting into a deep, warm, stagnant anticyclone (high pressure) system, which has the effect of causing the haze and large swing in temperature between day and night.
  • The time of occurrence is important: The warm days must follow a spell of cold weather or a good hard frost.

The conditions described above must occur between St. Martin’s Day (November 11) and November 20. For over 200 years, The Old Farmer’s Almanac has adhered to the saying, “If All Saints’ (November 1) brings out winter, St. Martin’s brings out Indian summer.”

Why is Indian summer called Indian summer? There are many theories. Some say it comes from the early Algonquian Native Americans, who believed that the condition was caused by a warm wind sent from the court of their southwestern god, Cautantowwit.

The most probable origin of the term, in our view, goes back to the very early settlers in New England. Each year they would welcome the arrival of a cold wintry weather in late October when they could leave their stockades unarmed. But then came a time when it would suddenly turn warm again, and the Native Americans would decide to have one more go at the settlers. “Indian summer,” the settlers called it.

Are you experiencing Indian summer conditions in your area?  Please post a comment below!


The 1985 Old Farmer's Almanac


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indian summer

My mother always said you can't have Indian Summer until you have Squaw Winter (frozen precipitation) Here in SE Mich we had graupel ( small weird shaped chunks of ice also called soft hail) on Nov 7th. We enjoyed several days in the 70s earlier a few days before. So according to Alice, we can now have an Indian summer.

Indian summer

The temp in Charlottesville today 11/05/15 was 78 degrees @ 4p.m. Frost occurred in October did we experience Indian Summer .

SW Michigan Indian Summer

We are certainly having an Indian Summer day on our homestead today, The Small House under a Big Sky in SW Michigan. It is 70, clear and our sky is a brilliant and bright blue. Our Lab Sassy is out on a blanket checking on a bone, our chickens are free ranging in the sunshine pecking at worms under the oak leaves. I am raking and cutting back perennials on our 5-acre property. I'll be eating lunch out under the trees soon. A glorious autumn day!!

Hudson Valley NY

We're having and going to have a great week here in the northeast with warm days of 70 degrees and then cool nights. Interesting cloud formations with blue and red skies, it will last all week into the weekend. Not sure if this is technically Indian Summer though, as it does not coincide with the dates given in the almanac.

Indian Summer

Had an Indian Summer last night in the mid North East. We had a cold spell for a few days and yesterday around 4:00 pm it gently blew in. I just stood on my porch for hours soaking it in until it was taken over with the chill of the evening. Praying it happens again tonight....we'll see