October at Ontario International Airport (ONT) is a strong month for leisure and business travel between Southern California and the Bay Area. Expect increased weekend traffic as Southern California residents travel to San Francisco for fall events, wine-tasting in Napa Valley or tech meetings in Silicon Valley. Airlines often publish competitive fares for midweek travel; use weekday departures for cheaper ONT to SFO flights and take advantage of early booking promotions. Pack layers for your return—ONT is inland and warmer than SFO in October—but allow early arrival times for peak morning departures. CTA: Book cheap flights from Ontario International Airport (ONT) to San Francisco International Airport (SFO) for October today to lock in the best fares.
Arriving at San Francisco International Airport (SFO) in October offers enjoyable fall weather for sightseeing in the city and quick access to Napa Valley harvest events. Expect cooler temperatures and occasional morning fog; pack a jacket and plan for layered clothing. For efficient transfers to San Jose, Oakland, Napa Valley or Berkeley, use BART, Caltrain or pre-booked shuttles—October sees increased demand during Fleet Week and weekend festivals so reserve ground transport in advance. CTA: Find and book the best ONT to SFO flights for October to secure favorable arrival times and public-transit connections.