What Causes Bay Area fog?

Asked by: Christina Morris

San Francisco’s fog is a meteorological phenomenon. Hot air rises away from the city, and the rising air mass creates a low-pressure zone. This zone sucks in cold, moist air from the Pacific Ocean, which brings moisture into the local climate. As the air cools below the dew point, Karl condenses.

Why is it so foggy in SF?

The Northern California climate gets very hot, especially in the summer, creating a low-pressure zone. San Francisco, on the other hand, is surrounded by water on three sides. The hot air rises, creating a vacuum for the cold, high-pressure, moisture-filled ocean air to rush in – hence, the fog.

What causes fog in northern California?

If you’ve ever tried to swim at the beach in Northern California, your chattering teeth will tell you that the water is cold. This cold water makes fog form. The cold water cools down the air above it, and cool air can’t hold as much moisture as warm air.

What type of fog is in the Bay Area?

What Type of Fog Occurs in San Francisco? San Francisco has a kind of fog known as advection fog. This kind of fog forms when a warm, moist air mass moves over a cooler surface. In San Francisco’s case, the moist air masses form off the coast, and the cooler surface is the Pacific ocean.

What is the foggiest month in San Francisco?

June is traditionally the foggiest month, but July and August are just as susceptible to fog as rain is from November through April. That should not discourage you from visiting SF.

How many days a year is it foggy in San Francisco?

108 days

NOAA data shows SF gets an average of 108 days of fog, and 105 days of clouds, a year. Heck, the City’s fog, nicknamed Karl the Fog, even has its own Twitter and Instagram accounts.

Which city has the most fog?

Cape Disappointment, Washington.
Washington is the most overcast state in the Union and sees 165 foggy days a year on average.

What causes fog in Monterey Bay?

The Monterey Bay region receives a stronger layer of fog because of the Monterey submarine canyon, whose deep, cold waters are flushed to the surface during seasonal upwelling. When gyres of warm wind coming over the Pacific hit the cold water in the Bay, the air chills and condenses to form fog.

Is SF getting less foggy?

However, as our climate has changed during the past few decades there has been a noticeable drop in the amount of Summer fog moving through San Francisco. The data below shows over the past 100 years we’ve seen a -34.5% decrease in fog which equates to about 3 to 4 hour less fog per day.

Why is Golden Gate Bridge foggy?

The Golden Gate Bridge has an influence in directing fog as it pushes up and pours down around the Bridge. “Advection fog” forms when humid air from the Pacific Ocean swoops over the chilly California current flowing parallel to the coast.

What are the foggiest neighborhoods in San Francisco?

The foggiest San Francisco neighborhoods include Ingleside, Mount Davidson Manor, Oceanview and Stonestown, which all receive an average of 12 hours of fog each day. The further southwest one traces the map, the foggier things get.

Is it foggy everyday in San Francisco?

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.

Does SF ever get warm?

Where’s the Sun? The bay counties surrounding SF get very warm in summer, often really hot, and see sunny skies every day, while San Francisco sits in its cool, foggy spot all summer.