As we start to batten down the hatches in preparation for the arrival of Mean Irene, it prmpted some pondering on the effect of weather in wargame -- or more precisely, the effect of extreme weather.
For the most part, until fairly recently in history, any sort of severe weather pretty much brought a halt to military proceedings. It was challenging enough to feed, clothe and move troops during normal times in the ancient era and most of the black powder era, without trying to do it in bad weather. The cases of major battles or campaign fought in extreme weather conditions or notable in part because they were so rare -- such as Washington's crossing of the Delaware.
Often bad weather caused battles to be postponed or even canceled. This all began to change as the Industrial Revolution gained steam and it became easier to supply armies and the general wealth increased. Railroads and steamships reduced the impact of bad weather on movements and fighting through poor campaign seasons and in the face of bad weatehr became more common.
By the 20th century warfare had reached the point where ideas such as "winter quarters" were obsolete and fighting continued year round through the seasons. It also expanded geographically into cold weather climates, jungles and deserts and other extreme locales.
One offshoot of this evolution is that modern-era wargames often have to take weather into account -- whereas it's an exceptional thing in ancient and black powder era games. But there's bad weather and then there's bad weather, and when we are talking about monstrous storms such as Irene, then there's no question of trying to represent tactical combat -- fighting would be impossible. But the time scale covered by most larger scale operational and strategic games doesn't lend itself to dealing with transient events such as hurricanes. A strategic level wargame depicting the entire US east Coast would probably involve turns covering a week or a month or more, whereas the entire hurricane event will be over in a week.
Here and there a game will through in a severe weather rule (Columbia Game's Pacific Victory and typhoons, for example) but generally it's ignored unless it's part of a larger climate. This does mean tha some historically significant storm events (such as the storm that aborted the probable Battle of Newport in the American Revolution) can't get an adequate representation.
Some new design techniques such as card-driven games may provide a way around that, though.