How reliable is San Francisco International Airport?

Across official performance history, flights from San Francisco left within 15 minutes of schedule about 79% of the time over 832,431 flights. That's a respectable but unspectacular operational record. Pair it with a low cancellation rate of 1.1%, so flights here rarely vanish outright. When a departure does run late, the typical delay is around 13 minutes.

On weather, San Francisco is an unusually calm-weather airport year-round. April is the calmest stretch for flying, scoring 97 out of 100 for favorable conditions, while December is the most disruptive at 90, driven mainly by low visibility & fog and high winds. The year is relatively steady, so no single month stands out as one to avoid on weather alone.

If you're connecting through SFO, give yourself room. Real itineraries sold through SFO bottom out around 64 minutes for a domestic connection, and international transfers around 66 minutes once immigration and a bag recheck are in the mix. Those are floors, not comfortable buffers — one inbound delay can erase them, so add margin when the connection matters.

None of this guarantees your specific flight — it’s the backdrop. To turn it into a booking, score real flights to San Francisco, read how we weigh it all in how the Peace of Mind Score works, and brush up with how to pick a reliable flight and avoiding weather delays.