Much has been said about the influence of climate on the history of warfare, and a lot has been made of the infamous Afghanistan winter. (For local conditions in Kabul click hereor here, and for a weather map click here.) Yet it's easy to exaggerate or misunderstand the influence of climate on combat. When a late 19^th-century Spanish governor of Cuba was asked to name his three best generals, he replied, "June, July, and August." A nice admission of the role of weather—and reminiscent of an observation made by Czar Nicholas I of Russia, who claimed that January was the great Russian military genius. The remarks of that Spanish governor were seriously flawed, however, and suggest that when one becomes dependent on climate to seal one's fortunes, then one becomes as much a hostage to the weather as its beneficiary. When the United States was drawn into the Cuban conflict in 1898, it successfully invaded the island on June 22 and had defeated Spanish colonial rule by July 17. So much for that Spanish general.

Afghanistan is no different. As the AccuWeather forecast for this country suggests, winter in this region of Central Asia is less extreme than what you might experience in St. Paul, Minn., or Fargo, N.D.; there's less precipitation, and the average winter temperatures are higher. What's very different about Afghanistan, in winter and in summer, is the speed with which meteorological conditions can change and how they vary from one part of a valley or a plain to another. One minute there's blue sky and sun; the next, there's a sand storm or snow. Or, as David Reynolds of the American Meteorological Society's committee on mountain meteorology explains: "You can have a 20- to 30-degree temperature change over a few miles. … I've been up in mountains in a helicopter working on a weather station, and all of the sudden, the clouds came in and we could hardly see. It can be extremely challenging to predict (weather) even as soon as 24 to 48 hours in a place like a Third World country, or in some parts of Europe." In Afghanistan the weather can change within minutes, and that is its most potent threat.