Everyone knows that time of year between late October and the end of November, long after summer has waved goodbye, and cold days have returned like an old but uninvited friend. Screens raised, storm windows lowered, wood chopped, and furnace primed, we've already boxed our shorts and T-shirts, covered the pool, rolled up the garden hose, and wheeled the lawn mower into the shed. We've traded our spade for a rake. We've taken out the flannel and wool. We've started eating soups again. We've begun to settle in.
Then it comes! Hills haze over. Wind stops. The world turns gentle and smoky, and the sky turns the deep blue of forget-me-nots. We forgive everything. We laze, and relish these strange warm days, these nights when the moon burns like a giant gas lamp. We forget about diminishing daylight, and revisit in our minds the long afternoons of July and August. We make the most of this meteorological benediction, for this is our last chance to bask in the sun. This is Indian summer.
A period of dry and unseasonably mild temperatures in the eastern and central United States, Indian summer occurs, ironically, when a polar air mass stagnates in the East. As cool air lingers and inhibited vertical flow concentrates dust and smoke near the ground, a clockwise rotation of wind pulls much warmer air from the deep South and Southwest.
Born of cold air, Indian summer often follows a killing frost, and may last from one to two weeks before a low-pressure system and accompanying cold front - grim reminders of the coming winter season - usher it away.
The origin of the term itself, however, is not so well understood. In perhaps the earliest written record of its usage, French essayist and colonial agriculturist Michel-Gillaume Jean de Crvecoeur, describing the New England weather in a letter dated Jan. 17, 1778, mentions the term. Yet his reference suggests that the expression was already popular, and doesn't explain its derivation.
Although almost all sources agree that the term originated in New England and is in some way connected to native American peoples - hence the now-pejorative adjunct - stories vary. One theory is that the term arose from the tribal practice of harvesting crops during this period in autumn. Still another suggests that the term was coined because some tribes launched their attacks against white settlers during the advantageously hazy weather.
One theory that doesn't concern native Americans offers a nautical explanation: that ships crossing the Indian Ocean preferred to sail during this fair-weather interval.
Whatever its etymology, this autumn weather event isn't native to America. Europe has its own version of it, generally referred to as Old Wives' summer. The British call it All-hallown summer. The Polish announce it God's Gift to Poland.
In Germany and northern Europe, Roman Catholics commemorate St. Martin of Tours - a bishop of the Middle Ages - with the feast day of Martinmas on Nov. 11. For country folk, Martinmas is a time to relax after the harvest and be festive, so they refer to autumn's occasional temperate blessing as a Martinmas summer or a St. Martin's summer.
By any name, though, this summer-in-autumn isn't guaranteed. Like all weather, it's not as predictable as we'd like it to be. Here in the States, it could occur several times during the season, or not at all. And with oddities like El Nio perplexing the world's weather, who's to say what will happen this year?
Still, I'm determined to remain hopeful. It'll be the millennium's last chance to warm our hearts, so I plan to keep one pair of shorts in the dresser.
(c) Copyright 1999. The Christian Science Publishing Society