Erica's Answer:It forms when the ocean water is much cooler than the air above land. We had quite a bit of sea fog during the month of July, since that ocean was stuck in the 50s for most of the month. When the air over land warms up and encounters the very cool air over that chilly ocean, the air over land is cooled down to its dewpoint. When air is cooled to its dewpoint, fog forms. A seabreeze usually develops, which causes the fog to drift inland.