How reliable is San Francisco International Airport?
Flights from SFO departed within 15 minutes of schedule in 81% of 791,535 flights in official BTS history — and weather is calmest in Apr. Here’s the full picture before you book.
Reliability score
on-time, cancellations & delays
Weather favorability
year-round climate
Origin-airport operations
What the departure punctuality at SFO looks like
On-time departures
across 791,535 flights
Source: BTS Airport Operations · data through 2026-06-25. Role-specific BTS departure history; advisory context, not a guarantee for any flight.
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Weather by month
When the weather works for you at San Francisco
A calm-weather score (0–100) for each month from decades of airport observations — how often conditions disrupt flying, not temperature. Higher is calmer.
Calmest month
Calmest flying weather of the year · 98/100 favorability
Roughest month
Most disruptive — low visibility & fog, high winds · 90/100 favorability
Connecting through SFO
How much layover you really need
Allow at least this between domestic flights at SFO. Below it, one small delay risks a misconnect.
International transfers add immigration and bag recheck — give yourself this buffer at SFO or more.
PlaneSane connection-time estimate tuned for SFO's terminal layout. We score every connecting itinerary against conservative connection floors.
The read on SFO
What the numbers say about flying through San Francisco International Airport
Across official performance history, flights from San Francisco left within 15 minutes of schedule about 81% of the time over 791,535 flights. That's a solid, better-than-average operational record. Pair it with a low cancellation rate of 1.2%, so flights here rarely vanish outright. When a departure does run late, the typical delay is around 12 minutes.
On weather, San Francisco is an unusually calm-weather airport year-round. April is the calmest stretch for flying, scoring 98 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. A domestic connection wants at least about 50 minutes, and international transfer wants roughly 95 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 PlaneSane Score works, and brush up with how to pick a reliable flight and avoiding weather delays.
Common questions about SFO
- How reliable is San Francisco International Airport (SFO)?
- Flights from San Francisco left within 15 minutes of schedule roughly 81% of the time across 791,535 flights of official history — a solid, better-than-average operational record. The cancellation rate runs about 1.2%. It's advisory context, not a guarantee for any single flight.
- What is the best month to fly from SFO for good weather?
- April has the calmest flying weather at San Francisco International Airport. December is the most disruptive, mainly from low visibility & fog and high winds.
- How much layover time do you need at SFO?
- Allow at least about 50 minutes for a domestic connection and about 95 minutes for an international one as a floor. These are minimums, not comfortable buffers — a single inbound delay can wipe them out, so add margin when you can.
Planning a trip through San Francisco?
Score real flights to and from SFO on reliability, weather, and connection safety — not just price.