Weird is a word rarely used to describe the weather in San Diego, especially in October, when the warm Santa Ana winds help push the marine layer toward the coast.
But coastal areas of the city are in the midst of an unusual period of thick, coming-and-going fog that has lasted more than a week and will persist for several more days, the National Weather Service said.
Fog was so thick Saturday that it made an 814-foot Japanese aircraft carrier nearly invisible during a port call in San Diego.
The region is experiencing a meteorological chain reaction. A massive high pressure system developed along the entire West Coast, causing temperatures to rise in places like Campo, which reached 102 degrees on Monday. Around the same time, sea surface temperatures off San Diego County dropped from 75 to 60 degrees. Cold, moist air has been colliding with the heat dome over the land, producing fog.
“A lot of people think it’s unseasonably cold on the coast right now, but it’s really not,” said Alex Tardy, a weather service forecaster. “If you went 1,500 feet above your head, you would be in about 85-degree air. “You have to think in three dimensions to imagine it, and that’s not easy.”
As surfers will tell you, it’s also unexpected. Ocean temperatures fluctuate. But such a sharp drop in them is not so common this time of year.
Tardy says the change was likely caused by upwelling, a phenomenon in which onshore winds hit the coast at an angle, pushing the warm top layer of the ocean away from the coast and allowing cooler water to rise to the surface.
Original Story
Why is San Diego having day after day of thick, cool fog?
