Summer in San Francisco can be very foggy. Here is just a moment in time, the week before the 4th of July. In most parts of the US and lots of the world, the temperature should be in the 70s or 80s Fahrenheit not 50s.
My favorite aspect of summer in San Francisco are the fog horns that start going at the Golden Gate Bridge on any given day at anytime. Did you know that:
Fog horns are required at the Golden Gate Bridge for the safe travel of vessels under the span. The foghorn signals are set by United States Coast Guard.If you come visit the city, don't worry about the weather. Pack light and pack layers. Bring a scarf! You can always buy an Alcatraz sweatshirt to take home with you.
There are two fog horns mounted on the south tower pier, about 20 feet or so up from the water.
There are three fog horns at mid-span that are located below the roadway level.
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. The fog hugs the ground and then the warm, moist air condenses as it moves across the bay or land. This is common near any coastline. Sometimes, high pressure squashes it close to the ground. By the way, the color of the Bridge is International Orange and was chosen in part because of its visibility in the fog.
The fog horns remind me of the Dashiell Hammett novels like The Maltese Falcon and film noir movies like The Thin Man. Now where is my trench coat and my fedora?