ONT (Ontario) to SFO (San Francisco) flights arrive on time 74% of the time. The most reliable airline on this route is United Airlines at 85%. The average delay is 70 minutes. Delays on this route are most often caused by air traffic and busy airspace.
Source: Bureau of Transportation Statistics. Updated May 2026.ONT → SFO
ONT (Ontario) to SFO (San Francisco)
ONT → SFO on-time performance by month
24
25
JanFebMarAprMayJunJulAugSepOctNovDec
Worse
Better
This route is delayed fairly often. About 74% of flights arrive on schedule.
Delays on this route are most often caused by air traffic and busy airspace.
Accurate?
United Airlines is significantly more reliable on this route at 85% on time vs Frontier Airlines at 55%.
Airline Comparison
United Airlines leads at 85% on time; Frontier Airlines trails at 55%.
Accurate?
Good to know
Departing from ONT
82% on timeTSA is currently ~13 min. Best time: 4 AM (about 5 min).
Arriving at SFO
80% on timeWhen flights into SFO are late, the average delay is 67 minutes. Build buffer if you have ground plans.
If connecting at SFO: TSA is ~21 min right now. Allow at least 60 minutes for a domestic connection.
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Data last updated May 2026. Source: Bureau of Transportation Statistics.