That is, it allows perspiration to evaporate through the material while keeping precipitation out. This is only somewhat true. No miracle fabric can completely evacuate your body heat if you're really riding hard. Another essential item for bicycling in the rain is a set of fenders, which should be standard equipment on every bike. But don't hesitate to install fenders, which will keep the wet weather slop off both you and your bike.
Extra caution is necessary while riding in the rain.
Your stopping capacity is also diminished in the rain. But if you're properly outfitted, riding in the rain isn't a terrible ordeal. You will certainly avoid a lot of those multi-car pileups that delay so many motorists during rainstorms.