Ironically, man-made areas channel the wind better and make the kilt fly around more. You really only need to worry about updrafts - anything horizontal will just whip the kilt about your legs.

Over 2,000 miles of hiking in the woods and across exposed mountain ridges, and my light 4-yard Bear Kilt never once blew up inappropriately (not that I'd have cared if it did, in the middle of nowhere). But in the city I'm always wary of a quick gust of wind. Hey though, if it happens (which is has once or twice), just look around, laugh, and shrug, and keep on walking.

Andrew.