I agree I've never seen a dense enough fog blanket to weaken the signal on a properly aligned dish. First suspect would be water getting into a fitting. Second would be check the signal strength on a sunny day on the transponders your locals are on, anything below 80 needs attention.I had this problem once before when I lived in a valley. While the fog can be dense enough to block the signal, my problem turned out to be a bad coax connector (old crimp style). I went and bought compression/PPC connectors and the problem went away. Over here at the new place, I have had fog, but never noticed any dropouts. Thunderstorms are a different story though.