The use of reactor waste heat to prevent the formation of advection fogs, particularly those off the coast of southern California, is investigated. It is found that the formation of these fogs can be inhibited by heating the surface of a cold band of offshore water which acts as a catalyst in the sequence of steps leading to fog formation. The surface water of the cold band (colder than the surrounding waters by 1 to 4°F) can be heated with reactor waste heat to raise its temperature to that of the surrounding waters. An estimate is given of the number of installed electrical megawatts required to produce the heat necessary to raise the temperature of the cold tongue a specified amount. The parameters of the cold tongue are based on available sea surface isotherms. The use of reactor waste heat to reduce the intensity (thereby improving visibility) in an existing advection fog is also examined. A mathematical model of advection fog, originally developed by Rodhe and used by Mc Vehil, is employed. It is found that a strongly nonlinear gain in visibility is achieved as the sea surface temperature (temperature at the fog base) is raised. A discussion is included of future studies required to investigate in more detail the feasibility of the ideas presented.