Like its famous neighbor to the north, Pacifica is beset with fog for a good many days of the year. There are essentially two types of fog that you see in Pacifica. The first is during the spring and summer months up until mid September. This is called advection fog and is the result of moist air passing over a cool surface from the wind and then is cooled. Advection fog in Pacifica can oftentimes keep summer days foggy until early afternoon. In the winter, the fog turns to convection fog which is a damp fog that lays low to the ground and often lasts all day.
Regardless of its from, fog is something to be taken very seriously. Anytime I encounter fog be it in Pacifica, San Francisco or even the Central Valley I always drive with my fog lights on. Slowing down and allowing extra spacing between cars is also wise.
Yes, Pacifica is famous for it's coastal fog at any time of the year! It could be 80 degrees in beautiful San Francisco and a foggy 65 here! Be careful driving on highway 1 to and from Pacifica because that's where the fog loves to creep and sometimes catches drivers off guard....so be careful!!