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Is San Francisco Bay’s Fog Disappearing?

What do you think? Are our summers less foggy these days? The New York Times recently reported San Francisco’s fog may be disappearing. There are a good number of scientists studying the phenomenon and, like most early scientific studies, the current consensus is a definite maybe. They interviewed gardeners in Golden Gate Park, Golden Gate Bridge painters and fog horn tenders, plus the Coast Guard and the Vessel Traffic Service. Most seem to feel there’s less fog, but the needed, long-term consistent measurements appear to be lacking.

Sailing into San Francisco Bay Fog
Here we go again, sailing out of the sun and into San Francisco Bay fog (and wind).
© 2022 Latitude 38 Media LLC / John

The Times wrote, “Every summer, fog breathes life into the Bay Area. But people who pay attention to its finer points, from scientists to sailors, city residents to real estate agents, gardeners to bridge painters, debate whether there is less fog than there used to be, as both science and general sentiment suggest.” Latitude 38 readers are the sailors in that sentence. What do you think? Is there less fog?

Ronstan Bridge to Bridge
There was plenty of fog on hand for the start of this year’s Ronstan Bridge to Bridge.
© 2022 Latitude 38 Media LLC / John

As Mark Twain noted and Herb Caen celebrated, San Francisco is the coolest major city in the continental US during the summer months. The fog can be a plus for a sweatshirt salesperson selling to a T-shirt-clad tourist on the Golden Gate Bridge. However, it makes sailing the Central Bay in the summer cool and challenging. The Coast Guard Golden Gate rescue station is one of the busiest in the country.

Entering the Golden Gate
Before the big bridge, lighthouses and fog horns, it was difficult to find the entrance to San Francisco Bay
© 2022 Latitude 38 Media LLC / Monica

According to the Farmers’ Almanac the lighthouse on Point Reyes National Seashore is one of the foggiest places in North America, running second only to Grand Banks, Newfoundland. The Farmers’ Almanac says it is also the windiest place on the Pacific Coast. Windier than Point Conception?

Sailing Sausalito Fog
Fog pouring over the Sausalito hills still feels as reliable as sunrise and sunset.
© 2022 Latitude 38 Media LLC / John

With lots of ship traffic, the fog, in addition to wind and current, is one of the many reasons there are so many wrecks on the Pacific Coast and in and around San Francisco Bay. Our recent podcast with Brian Crawford told just a few of the tales of Marin shipwrecks from Duxbury Reef on into the Bay. Better charts, GPS and other navigational aids have reduced the number of wrecks, but could reduced fog be helping? Most casual observers questioned in the story feel that there is less fog. If this is true and continues, it will affect everything from redwood trees, to crops, to sailing. Back in 2018 we were writing about people feeling that perhaps the winds were getting lighter.

Kites and Fog
Gray fog is the perfect backdrop for colorful kites.
© 2022 Latitude 38 Media LLC / John

We’re sure the first thing that followed the human development of language was debate about the weather. It continues today. The Rolex Big Boat Series is underway, with rain forecast for the last day on Sunday. How many times has that happened? Nome, Alaska, is about to be hit by a “superstorm” this weekend, with storm surges possibly 10-12 feet over normal. To us, the rhythm of the fog feels pretty normal, but we have a consistent, uneasy feeling about the weather, and our senses remain alert to the changes.

What about you? Do you think there is less fog?

9 Comments

  1. Craig Russell 2 years ago

    The article stated that there is 30% less fog than just a few years ago. Lots of debate and less agreement than anything. In my mind, this summer, the Pacific was a few degrees cooler than usual as was the bay. Not sure if that means more or less fog. And for those that don’t know, they have named our famous fog…Karl.

  2. Randall von Wedel 2 years ago

    Excellent SF Bay journalism.
    Kimble Livingston would probably agree.

  3. Kerry, vessel Cetacea 2 years ago

    I sail every 2-3 weeks in the N. Bay and we often have fog this time of year. I feel it may not be as heavy the past 2 years, usually a bank down the Slot and not extending in breadth to SF and Tiburon, but it still seems to be regular. The TWS has been ~25-32 kts the past year but has often averaged 32-34 kts in the previous 5 years at this time. I miss true gale-force sailing this time of year!

  4. Jim, SV Cheyenne 2 years ago

    Not sure if the San Francisco fog is decreasing, but pretty sure Cape Mendocino is the windiest spot on the California coastline.

  5. Brad Smith 2 years ago

    This is likely one for Max Ebb/Lee Helm, but my understanding is the fog is caused by the upwelling of cold water along the coast as the continent moves away from the Pacific Ocean. Unless that movement stops happening, there will be fog. Off hand I think over the last 20 years Santa Cruz has had less fog the last few years which is nice since “the marine layer” is not all that scenic, just cold.

    • Jeff Hoffman 2 years ago

      The San Francisco fog is caused by warm air mixing with cold water. The water is colder than it would otherwise be because of upwelling. Upwelling is caused by the wind patterns. If you notice, the ocean air at and near the coast gets warmer when we don’t get the usual summer winds, and the reason that the water is warmer is because there isn’t as much upwelling.

    • Jeff 2 years ago

      Sorry, I meant the ocean “temperature,” not “air.” Maybe I should turn off the music when I type. 🙂

    • Jeff 2 years ago

      The fog around here is caused by warmer air meeting cooler water. The ocean temperature here is cooler than it would otherwise be because of upwelling. The upwelling is caused by wind patterns. Notice that when we see warmer than normal ocean temperatures around here, it’s because the wind isn’t as strong as normal.

  6. Jeff Hoffman 2 years ago

    There is a plaque in Muir Woods that states that there is less fog on the coast around here than there used to be. That plaque was created in the 1950s.

    Less fog is almost certainly a result of global warming/climate change. Humans started extracting fossil fuels from beneath the surface of the Earth and burning them in the 18th century, and started burning a lot of fossil fuels about 150 years ago. Because burning of fossil fuels is the primary cause of global warming/climate change, there is little doubt in my mind that this is the cause of reduced fog. The plaque in Muir Woods was concerned with the need of the trees there to extract moisture from the fog and didn’t mention burning of fossil fuels or climate change, but global warming/climate change started before any of us were born. Its effects have just become severe enough that we can now see it for ourselves, with things like more unnatural heat waves and less fog.

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