I've never been in truly severe weather on a bicycle, but I have been in bad stuff several times on a motorcycle. Torrential downpours are bad, but it's not the wetness or the slippery road that's the real problem. The problem is that you can't see squat. The visor fogs up if it's down, and if it's up you're getting blasted in the face. No win. But the scariest thing I've encountered is wind. Wind is terrifying, especially when intermittent. It can easily blow you into another lane and straight into oncoming traffic. Be careful out there!