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Fun Facts About San Francisco Fog

Mark Twain is often misquoted as saying, “The coldest winter I ever spent was a summer in San Francisco.” In 1980 the San Francisco Court of Historical Review and Appeals cleared him of this “malicious misrepresentation,” contending that there was no written document attributing this remark to him.  San Francisco averages 160 sunny days a year and ranks above such sun spots as San Diego, Honolulu and Key West.

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Mark Twain is often misquoted as saying, “The coldest winter I ever spent was a summer in San Francisco.” In 1980 the San Francisco Court of Historical Review and Appeals cleared him of this “malicious misrepresentation,” contending that there was no written document attributing this remark to him.  San Francisco averages 160 sunny days a year and ranks above such sun spots as San Diego, Honolulu and Key West.

How Does It Happen?

Although fog can occur sporadically year-round, it mainly blankets the coastal Bay Area in the summer when hot inland temperatures create a low-pressure zone over Northern California's Central Valley.  The hot inland air rises and the heavier cold ocean air rushes in to replace it.  This flow from the high to the low pressure zone pulls the fog through the Golden Gate passage and into the Bay.

A Blast from the Past

In 1992 when the Coast Guard replaced their last Bay Area air fog horn with a high-pitched and high-tech electronic gizmo that goes "beep," the general public was outraged.  Local politicians, traditionalists and San Francisco-lore enthusiasts took up the cause until the Coast Guard promised to reinstall one of the old-fashioned blasters on Alcatraz Island.  The occasional sound of the baritone "BEEE-ohhhh" has been saved, despite its lack of usefulness in the modern-day marine world of radar, radio beacons and satellites in space.

Why the Golden Gate Bridge Isn’t Gold

Why is the Golden Gate Bridge painted "International Orange?"  The paint is not only the most resistant to showing wear from the elements of sun, wind, rain, salt spray and fog, but it's also the most visible through fog.

Foghorn Heralds San Francisco Giants Home Runs

Every Giants’ home run and win at AT&T Park is greeted with a blast from a foghorn. This is a tradition that dates from March, 1993 when the Giants played at Candlestick Park.  

Photo by David Yu.