San Francisco's Geography: Peninsula, Hills, and Iconic Setting

San Francisco occupies a dramatic geographic position at the tip of a peninsula separating the Pacific Ocean from San Francisco Bay. This unique setting creates the city's famous topography, microclimates, and iconic vistas.

Peninsula Location

The city sits on the northern end of the San Francisco Peninsula, a 48-mile (77 km) landform extending southward from the Bay Area's continental mainland. The peninsula is bounded by:

• West: Pacific Ocean—cold currents, fog, rugged coastline (Ocean Beach, Lands End)
• East: San Francisco Bay—sheltered waters, port facilities, bay bridges
• North: Golden Gate Strait—1-mile wide entrance to bay, spanned by Golden Gate Bridge
• South: Continues as San Mateo County (Daly City, Silicon Valley)

Topography: The Seven Hills (and More)

San Francisco's 46.9 sq mi (121 km²) encompass over 50 named hills. Key elevations:

• Mount Davidson: Highest at 928 ft (283 m)—city's geographic center
• Twin Peaks: 922 ft (281 m)—iconic panoramic views
• Mount Sutro: 909 ft (277 m)—Sutro Tower landmark
• Nob Hill, Russian Hill, Telegraph Hill: Historic neighborhoods with cable car routes
• Bernal Heights, Diamond Heights, Glen Canyon: Residential hills with distinct microclimates

Geological Foundation

Bedrock is primarily Franciscan Complex—chaotic mélange of sandstone, shale, chert, greenstone, and serpentine from ancient subduction zone. Soils vary from thin rocky slopes to filled marshlands (Marina District, Financial District, Treasure Island). Active seismic zone: San Andreas Fault (west), Hayward Fault (east).

Hydrology

No natural lakes. Historic creeks (Mission Creek, Islais Creek) mostly culverted. Water supply from Hetch Hetchy Reservoir (Yosemite) 167 miles away.

Golden Gate Bridge

Completed 1937, 1.7-mile (2.7 km) suspension span connecting San Francisco to Marin County. International Orange color chosen for fog visibility. Carries 112,000 vehicles daily. Symbol of the city's connection to the Pacific world.

Microclimates

Hills create dramatic weather variations: western neighborhoods (Sunset, Richmond) foggy/cool; eastern neighborhoods (Mission, SoMa) sunnier/warmer. Temperature differences of 10-15°F (5-8°C) over few miles are common.