San Francisco experiences cooler summers due to the cooling effect of the California Current and its proximity to the ocean.

San Francisco's cooler summer temperatures are largely due to the California Current and its closeness to the Pacific Ocean. The cold current flowing along the coast brings cool air and fog, which help to moderate the city's temperatures, especially in the summer. This coastal influence prevents the city from experiencing the extreme heat seen in inland California cities like Sacramento. While these inland areas are farther from the ocean and lack this cooling effect, San Francisco enjoys a more temperate climate year-round, with cooler summers and milder winters compared to other parts of the state