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Written by: William R. Deedler, Weather Historian
National Weather Service Detroit/Pontiac, MI
Fall, 1996

An early American writer described Indian Summer well 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." This passage belongs to the writer John Bradbury and was written nearly an "eternity" ago, back in 1817. But this passage is as relevant today as it was way back then. The term "Indian Summer" dates back to the 18th century in the United States. It can be defined as "any spell of warm, quiet, hazy weather that may occur in October or even early November." Basically, autumn is a transition season as the thunderstorms and severe weather of the summer give way to a tamer, calmer weather period before the turbulence of the winter commences.

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 references make note of the fact that a true Indian Summer can not occur until there has been a killing frost/freeze. Since frost and freezing temperatures generally work their way south through the fall, this would give credence to the possibility of several Indian Summers occurring in a fall, especially across the northern areas where frost/freezes usually come early.

While almost exclusively thought of as an autumnal event, I was surprised to read that Indian Summers have been given credit for warm spells as late as December and January (but then, just where does that leave the "January Thaw" phenomenon?). Another topic of debate about Indian Summer has been "location, location". Evidently, some writers have made reference to it as native only to New England, while others have stated it happens over most of the United States, even along the Pacific coast. Probably the most common or accepted view on location for an Indian Summer would be from the Mid-Atlantic states north into New England, and then west across the Ohio Valley, Great Lakes, Midwest and Great Plains States. In other words, locations that generally have a winter on the horizon! But then, what about the king of winter weather in the United States, Alaska? Do they have an "Indian Summer", or something similar? Some places in Alaska are lucky to have a "summer", let alone an Indian Summer! One would certainly have to throw out the notion of it usually happening in October or November, when, winter generally has already taken an aggressive foothold on much of the state. What about other locations that come to mind, The Rocky Mountain States and parts of Canada, particularity in the east and south? Note: If anyone reading this has any information on Indian Summers in those areas questioned, or just thoughts on Indian Summers in general, drop us a note at

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/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 is the general weather map.

Now we come to the origin of the term itself, "Indian Summer". Over the years, there has been a considerable amount of interest given to this topic in literature. Probably one of the most intensive studies occurred way back around the turn of the century. A paper by Albert Matthews, written in 1902, made an exhaustive study of the historical usage of the term. Evidently, the 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 13th, 1794. The journal was kept at a town called Le Boeuf, which was near the present day city of Erie, Pennsylvania. Matthews however, uncovered an earlier usage of the term in 1778 by a frenchman called St. John de Crevecoeur. It appeared in a letter Crevecoeur wrote 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 the writer 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, an earlier explorer or possibly an Indian tribe?

Now, after looking at all of this, the question you might ask yourself is, "Does the term 'Indian Summer' really have anything to do with Indians?" Again, there is host of possibilities, read on...

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, smokey conditions. But Albert Matthews pointed out that the Indians also did this at other times of the year. Other possibilities include; the Indians made use of the dry, hazy weather to attack the whites before the hard winter set in; that this was the season of the Indian harvest; or, that the predominant southwest winds that accompanied the Indian Summer period were regarded by the Indians as a favor or "blessing" from a "god" in the desert Southwest. Another idea, of a more prejudicial origin, was that possibly the earliest English immigrants equated Indian Summer to "fools" Summer, given the reliability of the resulting weather. Finally, another hypothesis, not at all in the American Indian "camp" of theories, 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 the "Indian Summer", or fair weather season. Several ships actually had an "I.S." on their hull at the load level thought 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. Given the fact it has been centuries since the term first appeared, it will probably rest with its originators. 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/freeze. There may be several occurrences of Indian Summer in a fall season or none at all.

Since Indian Summers are fairly common, it would be interesting to find out if there is any correlation between the years that had no Indian Summer (in a particular area) and the type of winter weather that followed. Oh well, possibly another time and another article but enjoy the Indian Summer while its around, because one thing is for certain, it never lasts!