San Francisco, where just about everyone (and especially Tony Bennett) famously leaves their heart, is also known for its fog. The fog is so famous, in fact, that locals even gave it a name—Karl—and a cheeky fan page on Twitter. While it's not exactly the sunny California weather visitors may expect, the cool fog does lend the city of San Francisco a mysterious and romantic atmosphere.
As Carl Sandberg wrote in his well-known poem "Fog," "The fog comes on little cat feet. It sits looking over harbor and city on silent haunches and then moves on." Sandburg wrote these evocative and memorable words not about San Francisco, but rather about Chicago. But it describes how the ever-present fog feels in San Francisco to a T. If you visit in the summertime, you are sure to witness this softness creeping over the harbor and around the Golden Gate Bridge. You might see it at other times of the year, but summer is the most likely.
What Causes Fog
Fog covers San Francisco the most in the summer when the cold wind off the Pacific Ocean hits the heat of inland California. As the hot inland air rises, the cool ocean breeze off the Pacific replaces it, creating the fog effect. This flow of air to the low-pressure zone over Northern California's Central Valley pulls the fog through the Golden Gate passage and into San Francisco Bay.
When and Where to Find the Fog
It's common to see fog in the summer, but you can't count on it every day. If you're looking for a romantic fog adventure, be spontaneous. Fog can be seen in San Francisco Bay pretty dependably starting in June and lasting through August. The fog usually rolls in during the early morning, then burns off by the afternoon, revealing sunny, clear skies, until it returns again in the evening. So make sure to set your alarm in the morning or prepare to stay up later to see it.
The fog creeps in between the arches of the Golden Gate Bridge towers, then flows over the Marin Headlands, until it hits the shoreline piers. Very rarely is the whole city enveloped by fog; most often, some areas of San Francisco are still visible.
Best Places to View the Fog
When the fog is in, a prime way to see it, to be immersed in it, is to walk across the Golden Gate Bridge. If that's not you, you can get a pretty splendid view of the fog along Crissy Field, the Golden Gate Promenade, Marina Green, and Fisherman's Wharf, where there's significantly less wind and wetness to make you cold. Other favorite spots to see the fog include East Baker Park, Mount Tamalpais State Park, and Tilden Regional Park.
One of the best views requires a bit more effort. Climb high above the mist on top of one of San Francisco’s hills and look down for a bird's-eye view of the Bay, the Golden Gate Bridge, and the city skyline. From here, you can spot the tips of the Coit Tower and the Transamerica Pyramid rising from the soupy fog.
Travel Tips for the Foggy San Francisco Summer
Sometimes the overcast, foggy weather can stay along the coast for days, depending on the pressure above the marine layer. Called "June Gloom" by locals, these chilly, damp days—with average temperatures in the 60s—are not what tourists expect when they head to California in the summertime. So, if you plan on visiting the Bay Area any time between June and August, make sure to pack a sweatshirt, jeans, and warm layers in case you get caught in the fog. You'll also want to leave extra travel time as planes tend to get delayed flying in and out of the San Francisco International Airport when fog rolls in.
For those who prefer sunshine, it's best to book your San Francisco trip between September and November, when the days are actually warmer than in the summer. During the fall, temperatures are comfortable and hover in the mid-70s, with clear, cloudless skies. This is also prime time for beachgoers. If you want to hit the sand, you should still pack a light jacket for the brisk sea breeze.