When rugged terrain rises off a rough sea, the combination often creates a climate ripe for extreme weather. But the San Francisco Bay Area experiences clement, stable skies much of the year. That’s not to say that severe storms can’t and don’t lash the region (they do, although almost exclusively in the winter months), but for most of the year, temperatures, winds, and precipitation can best be described as moderate.
Nevertheless, while much of the interior portion of the Bay Area experiences wider swings in temperatures and fewer days of low-lying clouds, much of the allure of the region comes from the juncture of land and sea—at the Golden Gate itself and above adjacent San Francisco—in the form of fog. Summer fog originates from the cold waters of the Pacific, where deep, cold currents rise to the surface, and temperature and pressure differences between the sea and land (and within the topography of the land itself) push and pull banks and streamers of the silent fog throughout the area. Often, summer afternoon temperature gradients are great enough between the Pacific and inland portions of the Bay Area that continuous winds as high as 35 mph sweep long ropes of fog in through the Golden Gate, cloaking and then unveiling portions of the Golden Gate Bridge.