How cold was Mark Twain's summer in San Francisco?

Unfortunately, Twain's twin prose, “The coldest winter I ever spent was a summer in San Francisco,” has long been considered fictitious by San Francisco history buffs and literary scholars alike.

The ruling was even reached in one of a series of mock trials held in real City Hall court rooms by the San Francisco Court of Historical Review and Appeals in the late 1970s and early 1980s to set the record straight on the city’s history — with  a hearty sense of humor, the LA Times reported in 1985. 

Other sources have gone on to discredit the popular San Francisco pondering from one of American literature's most legendary figures. In 2002, Snopes deemed the attribution false. Again, in 2012, Anchor Brewing published a blog post tracing the closest tepid reference to weather found in Twain’s correspondence and writings. In a letter from 1880, also mentioned by Snopes, the writer penned a friend, congratulating him for receiving placement away from Paris, which Twain deemed “Paris the cold, Paris the drizzly, Paris the rainy, Paris the Damnable.”

He riffed, adding in a quote from the 1700s actor James Quin. “More than a hundred years ago, somebody asked Quin, ‘Did you ever see such a winter in all your life before?’ ‘Yes,’ said he, ‘last summer.’ I judge he spent his summer in Paris,” wrote Twain. 

And still, in 2021, the author-less quote glared at bathroom-goers at the Salesforce WeWork, boasting Mark Twain as its scribe. It’s heard in the foggy breath of bar-goers on summer nights and the chatter of BART-riders as they settle into warm cars. 

So we still have to wonder, especially in a winter so frigid, just how cold were Mark Twain’s San Francisco summers?

Twain, whose real name was Samuel Clemens, arrived in San Francisco by stagecoach in 1864. He spent 18 months in Northern California, working as a writer and journalist, according to FoundSF.  

In 1864, the summer saw mean temperatures running from 57 to 61 degrees from May through September, according to data from a report on the history of SF’s weather observances. That winter’s coldest months, January and December, had mean cold temperatures of 51 and 52.5 degrees respectively. At its coldest, The City’s temperature dropped to 38 degrees. The next year saw similar trends: a summer mean of 60 to 62 degrees in, a winter mean between 47 and 55, and an annual low of 27 degrees in December. Temperatures reached up to 91 degrees in October of ‘64 and September of ‘65. 

The low this February was 39 degrees, according to data from the National Weather Service. The average temperature for the month was 50.5 degrees. January’s lowest dip was 36 degrees, on the 31st of the month. But the average temperature was 53.8 degrees — slightly above Twain’s first averages, but a notch below the coldest day he may or may not have been in town to experience.