How reliable is San Francisco International Airport?
Flights from SFO departed within 15 minutes of schedule in 80% of 804,853 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 804,853 flights
Source: BTS Airport Operations · data through 2026-08-08. Role-specific BTS departure history; advisory context, not a guarantee for any flight.
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
Based on 35 sellable domestic itineraries seen through Google Flights. Median observed layover: 193 min.
Based on 75 sellable international itineraries seen through Google Flights. Median observed layover: 167 min.
Observed windows come from normalized SearchAPI / Google Flights itineraries. They are not official airport MCTs. 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 80% of the time over 804,853 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. Real itineraries sold through SFO bottom out around 107 minutes for a domestic connection, and international transfers around 72 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 80% of the time across 804,853 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 107 minutes for a domestic connection and about 72 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.
Reliability guides
Planning a trip through San Francisco?
Score real flights to and from SFO on reliability, weather, and connection safety — not just price.