I was running ahead of time this morning before I left the house, so I turned on the news to watch the weather. They were warning of heavy fog, even though it didn't seem particularly foggy at my house. So I swapped all my gear from my single speed, which I had planned to ride, to my touring bike, which has a much brighter tail light. Good move. It got very foggy as I left my neighborhood with very low visibility on some roads. Pulled over at one point for a police car and fire truck with their sirens on, and when I got farther up the road saw that they were responding to a motorcycle accident. That was creepy.