2007-10-24 / News

Why do we call it Indian summer?

Leaves have changed, often past their peak color, when the warm, hazy southern air blankets the region, sometimes lasting for as much as a week. Indian summer has arrived. But just what is Indian summer, and where did the name come from? Blackberry winter which usually occurs in mid spring, and Indian summer usually in mid fall, are weather phenomena that are common enough to have acquired a nickname. Indian summer can be defined as "any spell of warm, quiet, hazy weather that may occur in October or even early November."

The term Indian summer is generally associated with a period of considerably above-normal temperatures, accompanied by dry and hazy conditions ushered in on a south or southwesterly breeze. Several historical references make note of the fact that a true Indian summer can not occur until there has been a killing frost or freeze.

Writing about life in America, an early American writer well described Indian summer when he wrote, "The air is perfectly quiescent and all is stillness, as if Nature, after her exertions during the Summer, were now at rest." Although written in 1817, this passage belongs to the writer John Bradbury, this rather flowery description is still relevant today.

The usage of the term of Indian summer dates far back in American history. According to the research of Detroit, Mich. National Weather Service employee Bill Deedler, who describes himself as a "weather historian", the term Indian summer dates back to the 18th century in the United States. Credit for the first usage of the term was mistakenly given to a man by the name of Major Ebenezer Denny, who used it in his journal dated October 13, 1794. The journal was kept at a town called Le Boeuf, which was near the present day city of Erie, Penn. But an earlier usage of the term was discovered in a letter written by a Frenchman named St. John de Crevecoeur, dated German flats, 17 Janvier, 1778. The following is a translation of a portion of the letter:

"Sometimes the rain is followed by an interval of calm and warmth which is called the Indian summer; its characteristics are a tranquil atmosphere and general smokiness. Up to this epoch the approaches of winter are doubtful; it arrives about the middle of November, although snows and brief freezes often occur long before that date."

Since Monsieur Crevecoeur says, "it is called the Indian Summer," obviously one could argue that term would have had to been used before him and became popular, but by whom? It is a question of weather lore lost to history.

There is debate over the origin of the term itself, Indian summer. One explanation of the term Indian summer might be that the early native Indians chose that time of year as their hunting season. This seems reasonable seeing the fall months are still considered the main hunting season for several animals. Also, the mild and hazy weather encourages the animals out, and the haziness of the air gives the hunter the advantage to sneak up on its prey without being detected. Taking this idea one step further, Indians at that time were known to have set fires to prairie grass, underbrush and woods to accentuate the hazy, smoky conditions. There are some rather derogatory explanations as to the origin of the Indian summer terminology which did not come about until the early 1900s. Those theories are discounted today by linguists who track the history of word origins.

Another hypothesis, having nothing at all to do with Native Americans, was put forward by an author by the name of H.E. Ware, who noted that ships at that time traversing the Indian Ocean loaded up their cargo the most during Indian summer, or fair weather season. Several ships actually had an "I.S." on their hull at the load level thought to be safe during the Indian summer. In any event, there are several theories or possibilities of the explanation and origin of the term Indian summer, yet no one theory has actually been proven.

A typical weather map that reflects Indian summer weather involves a large area of high pressure along or just off the East Coast. Occasionally, it will be this same high pressure that produced the frost or freeze conditions only a few nights before, as it moved out of Canada across the Plains, Midwest and Great Lakes and then finally, to the East Coast. Much warmer temperatures, from the deep South and southwest, are then pulled north on southerly breezes resulting from the clockwise rotation of wind around the high pressure. It is characteristic for these conditions to last for at least a few days to well over a week and there may be several cases before winter sets in.

Such a mild spell is usually broken when a strong low pressure system and attending cold front pushes across the region. This dramatic change results from a sharp shift in the upper winds or jet stream from the south or southwest to northwest or north. Of course, there can be some modifications to the above weather map scenario, but for simplicity and common occurrence sake, this will be the general weather map.

All in all, even with the variety of opinions on this weather (or seasonal) phenomenon, the most popular belief of Indian summer is as follows: It is an abnormally warm and dry weather period, varying in length, that comes in the autumn time of the year, usually in October or November, and only after the first killing frost or freeze. There may be several occurrences of Indian summer in a fall season or none at all.

Enjoy Indian summer while it's around, because one thing is for certain, it never lasts!

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