Fog in San Francisco
When warm air cools, water vapor condenses to form a mist. When this mist is on the earth's surface it's called fog.
Fog forms off the coast of San Francisco. Air in the coastal valleys of the Bay Area and the Central Valley of California heats-up during the day. The air in these locations expands and rises. This displaced air must be replaced. Air is sucked from off-shore, where fog has formed and in through the Golden Gate. San Francisco just happens to be in the path of the fog and wind as the fog makes its way towards these hotter areas.
Link to a hands-on fog making activity.
See if there is fog in San Francisco.
What's the weather and wind speed in San Francisco
What's the weather and wind speed in Sacramento
