How San Francisco’s airport works: fog, terminals and getting there

San Francisco International Airport (SFO) was built on landfill at the bay's edge in 1927, when the importance of wetlands was not understood, and that choice still shapes it: wetlands lie to the west and the bay to the east, and environmental laws stop it from filling in either. Wikivoyage's guide explains how an airport that cannot grow works for a traveler, from fog delays to the trains and shuttles that reach it.

Map of the airport (Photo: PerryPlanet, CC0)

The airport in outline

SFO sits about 15 miles (24 km) south of downtown San Francisco and 35 miles northwest of San Jose, on the western side of the bay. About 30 years after it opened, the airport began adopting the centralized terminal design it has now. The layout is easy to follow and is reached through a single highway interchange on U.S. Highway 101, but the guide says many interior spaces that looked modern by 20th-century standards now feel short and crowded.

According to the guide, SFO is second only to Los Angeles in passenger traffic within California, is among the 10 busiest airports in the United States and the top 25 in the world, and handles more than 50 million passengers a year. The guide notes a heavy focus on East Asian routes, and two of the world's top ten longest flights leave from San Francisco, to Singapore and Bengaluru.

There are four terminals, three domestic and one international, with seven concourses in a circle around the parking and transport facilities. Some domestic flights leave from the international terminal and some international flights to Canada from the domestic terminals. United operates a domestic hub from Terminal 3 and an international hub from the International Terminal, and Alaska Airlines a hub from Terminal 1. A guide note dated 2026 says Boarding Area F in Terminal 3 was being renovated, with its main corridor closed and some of United's domestic operations moved to Terminal 2.

Fog and runways

The two sets of parallel runways are too close together for simultaneous arrivals in low visibility. In clear weather both runways in one direction can be used; when low clouds roll in, only one can. Air traffic control then holds inbound flights, either in the air or at the departure airport. The guide's advice: leave extra time for connections or anything time-sensitive.

Arriving and leaving

• International arrivals (except flights from airports with U.S. preclearance) pass immigration in the International Terminal, then collect baggage and go through customs. There is no international transit zone. Passengers connecting onward can drop checked bags in an area just after customs.
• Domestic arrivals come in on the departure level inside security, and since all gates are connected after security, connecting passengers do not clear it again.
• Departures check in at their airline's own terminal. Check-in areas are narrow and each boarding area has a single security checkpoint, so lines can be long at busy times. There is no direct airside link between the A and G gates; staying airside means walking the long way round through the domestic terminals.

Getting to the airport

The guide also notes that robotaxi service was available at the airport in a limited form, with a waitlist.

Getting around

AirTrain platform at International Terminal G station (Photo: Pi.1415926535, CC BY-SA 3.0)

The AirTrain is free and runs around the clock. The Red Line loops clockwise through the terminals, the international garages, the Grand Hyatt hotel and the BART station at Garage G. The Blue Line, which runs counterclockwise, stops at all the same places and also at West Field Road, the Rental Car Center and Long-Term Parking. Before security, all terminals can be reached on foot; the Rental Car Center and long-term parking cannot. In the early morning, sections of track close for maintenance, with signs and announcements explaining how to bypass them.

While you wait

The guide lists a wide variety of activities. There is an aviation museum and library before security in the International Terminal, set up as the airport looked in the 1930s, and an SFO Museum that rotates art exhibitions through the terminals. There is a large public art collection, kids' play areas, yoga rooms, a plane-spotting terrace in Terminal 2 and an outdoor terrace in the International Terminal with sculptures and a garden of drought-resistant plants. Free Wi-Fi covers all terminals and concourses, and domestic terminals have power sockets at most seats and in the walls.

Plants on the Outdoor Terrace (Photo: Mx. Granger, CC0)

For a long layover, BART reaches San Francisco in about half an hour. Sleeping at the airport, the guide says, is not a good option: the padded benches in the domestic baggage claims are open to the public, and airside seats mostly have fixed armrests. One hotel stands within the airport grounds, and cheaper ones line El Camino Real in Millbrae and San Bruno. Plane enthusiasts can watch takeoffs and landings from bayside parks in Millbrae and Burlingame.

A departure board at SFO (Photo: quinn norton from Excellent Question, CC BY 2.0)

Sources

• Wikivoyage, "San Francisco International Airport" (https://en.wikivoyage.org/wiki/San_Francisco_International_Airport), by its contributors, licensed under CC BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0/). Changed here: rewritten and condensed in hubnx's own words; prices, hours, phone numbers, restaurant, lounge and hotel listings and some photos left out. Photos are used under their own licenses, credited in their captions.
• Wikivoyage contributors; rewritten in hubnx's own words.