"I had reckoned much on the Indian summer, of which I had read such delightful descriptions, but I must say it has fallen far below my expectations. Just at the commencement of this month (November) we experienced three or four warm hazy days, that proved rather close and oppressive. The sun looked red through the misty atmosphere, tinging the fantastic clouds that hung in smoky volumes, with saffron and pale crimson light, much as I have seen the clouds above London look on a warm, sultry spring morning."
... "I think the notion entertained by some travellers, that the Indian summer is caused by the annual conflagration of forests by those Indians inhabiting the unexplored regions beyond the larger lakes is absurd. Imagine for an instant what immense tracts of woods must be yearly consumed to affect nearly the whole of the continent of North America: besides, it takes place at that season of the year when the fire is least likely to run freely, owing to the humidity of the ground from the autumnal rains. I should rather attribute the peculiar warmth and hazy appearance of the air that marks this season, to the fermentation going on of so great a mass of vegetable matter that is undergoing a state of decomposition during the latter part of October and beginning of November. It has been supposed by some persons that a great alteration will be effected in this season, as the process of clearing the land continues to decrease the quantity of decaying vegetation. Nay, I have heard the difference is already observable by those long acquainted with the American continent." ...
as to the far-famed Indian summer it seems to have taken its farewell of the land, for little of it have we seen during three years' residence. Last year there was not a semblance of it, and this year one horrible dark gloomy day, that reminded me most forcibly of a London fog, and which was to the full as dismal and depressing, was declared by the old inhabitants to be the commencement of the Indian summer; the sun looked dim and red, and a yellow lurid mist darkened the atmosphere, so that it became almost necessary to light candles at noonday. If this be Indian summer, then might a succession of London fogs be termed the "London summer," thought I, as I groped about in a sort of bewildering dusky light all that day; and glad was I when, after a day or two's heavy rain, the frost and snow set in."
I have experienced what I had thought was Indian Summer many times, but I have never found that I couldn't see where I was going or needed to turn on the lights in the middle of the day, or that the atmosphere seemed to be full of smoke.