Last time I drove to SF from LA, there was thick fog and VERY light traffic. In the clear spots, 100+ MPH was typical. In the dense foggy areas, visibility was 80-100 feet at best. I slowed to about 40-50 MPH. There was no way I could drive faster and still have time to stop it there was a car stopped in front of me.
Most drivers slowed to about 90 MPH and plowed through the fog.
