San Francisco is divided up into districts, each with a history. SFO airport is south of the city and is subject to the same foggy conditions as the Golden Gate Bridge and the rest of San Francisco. Most afternoons, you’ll seeing the cold fingers of fog making their way into the lowest areas and bringing the temperature down dramatically.
Here is a map showing the peninsula that makes up the San Francisco districts and the Bay Area:
The airport is down toward the south end of the peninsula. The planes generally take off into the wind while going north, and land by coming up from the south bay over the water and arriving on parallel runways. Sometimes you see another plane alongside yours, descending and coming in for a landing at the same time. It can be a little odd to see another plane seem so close when you are landing, but the pilot usually comes on the intercom and announces that you will see another plane landing at the same time, and not to worry. So sit back and enjoy the ride into SFO!