It was fine in the park, but I was having serious doubts on my drive down. The fog was so thick you could barely see the other cars (many of which had no lights on, making them effectively invisible) and it rained so hard at times that the road was standing in an inch of water. (Baltimore Beltway and 70)
Driving through your viewfinder helps, I'm sure.
I was looking through the windshield! Just holding my phone out to the side. ;-)