San Francisco fog

Fog is a common weather phenomenon in the San Francisco Bay Area and along the California coastline south to the northwest coast of the Baja California Peninsula, driven by a combination of factors especially prevalent in summer. A separate type, tule fog, can occur in winter, and the two can occasionally coincide in the Bay Area. Some studies suggest the frequency of Bay Area fog has decreased since 1951, potentially linked to climate change and other human-driven change, though other researchers argue the data are insufficient or point to contrary results.