I've been caught by storms 25 miles from home - didn't check the weather of course - and have missed having some nice weekend rides by being too concerned with the forecasts. There is a happy medium in there somewhere. Mostly I can check the radar and plan a few hours ahead, but that means being pretty flexible about it.

Commuting is a little different because I'll commute every day, rain or shine. But I'll still check the weather, morning and evening, and if it's anything but clear I look at radar and satellite to make a plan. I used to get a kick out of storm-riding, but it's just common sense to avoid the worst of it if you can.

My commute is 8 miles, taking me under half an hour in the worst conditions, so I don't really worry that much about it. It's just enough to make a difference, but not enough to be dangerous or extreme. There are some whose ride is a mile and half, and they tend to advise that the rain is nothing, just wear a poncho or something. I know some others who are going 15 or 20 miles, and they do take it seriously and skip it if the weather is too threatening. It really does depend on how long you're going to be out there, and I think that all of these opinions should be taken in context.