As a kid, I lived not far from Glen Canyon. Up the hillside a ways. It was hardly ever warm, except on those couple of days each September when all the charges reverse. Almost always cool to cold and windy, up near Twin Peaks, and the coastal fog came through at ground level rather than the usual low overcast (we were *in* the low overcast). I don't ever remember seeing "tule fog" though - Glen Canyon is open at the bottom (Glen Park area) so the cold air drainage wouldn't really get stopped up and produce much if any fog there. First real experience with it was in Santa Rosa. Where I live now, it can be amusing when the fog starts forming over a sports field in use for soccer practice - at times, with the lights, it seems like the players can see each other, but can only see the ball when somebody kicks it up out of the fog a bit.

Stop - Look - and LISTEN is the rule in tule fog. Visibility is 1/4 mile or less in the good stuff. Driving is a b***h; you have to be slow, watch carefully, stop at intersections and listen for cross traffic (drive with the window open, and shut off the d**n radio). Unprotected grade crossings are deadly, because you probably won't see the train until it's about to hit you; must listen for activity farther down the line in either direction, and there's any glow in the direction of the tracks Get Off Them Immediately. Some school buses in the San Joaquin Valley have radar to help with navigating country road intersections.