✈️ Flight Guide: Ontario (ONT) → San Francisco (SFO)

May in the Bay Area features running events, neighborhood street fairs, and professional sports. Bay to Breakers (typically early May) draws thousands and can affect hotel rates and rideshare wait times. Major-league baseball (San Francisco Giants home games) continues throughout May at Oracle Park, increasing weekend demand. Wine-focused events in Napa and Sonoma pick up in May as the weather improves. Travelers flying ONT→SFO should check event calendars and pre-book ground transport during festival weekends to avoid delays.

For May travel between Ontario International Airport (ONT) and San Francisco International Airport (SFO), the best time to fly for value and punctuality is midweek (Tuesday–Thursday) and early-morning departures. Avoid peak Friday afternoon and Sunday evening slots when business and leisure travelers compete for seats. If your trip coincides with Bay Area events or holiday weekends in May, plan at least 2–3 weeks ahead and consider flexible return dates to reduce costs.

Nonstop flights from Ontario International Airport (ONT) to San Francisco International Airport (SFO) are the fastest and typically most convenient for May travel, averaging around 1 hour 15 minutes airborne time and minimizing connection risk. Connecting itineraries via Los Angeles (LAX) or San Jose (SJC) can be cheaper on rare occasions but add transfer time, baggage wait, and higher disruption risk. For business trips or short weekend getaways, choose nonstop service when available; for significant cost savings or when nonstop seats are sold out, consider a single-connection itinerary with a long layover buffer.

Compare carrier fares and book the best ONT to SFO flight for your May travel: check schedules, baggage policies, and loyalty perks before purchasing.

Pack layers: Ontario is warm and dry in May while San Francisco is cooler with a coastal marine layer. Bring a light jacket and comfortable walking shoes for city exploration. For security, follow TSA 3-1-1 liquid rules and review carry-on allowances for your chosen airline. Reserve rental cars in advance for Napa or Monterey day trips, and use BART from SFO for quick city access. Allow buffer time for event weekends and use mobile boarding passes to speed check-in and boarding. CTA: Prepare your May itinerary now — compare flights and book early for the best ONT to SFO options.

Average airborne time from Ontario International Airport (ONT) to San Francisco International Airport (SFO) is about 1 hour 10–25 minutes; gate-to-gate schedules usually list 1 hour 30 minutes to account for taxi and ground. In May, expect multiple morning and evening flight windows, with the highest frequency on Fridays and Sundays. For reliable travel, pick early-morning departures (6:00–9:00 AM) to avoid afternoon weather or traffic-related delays. Check carrier schedules for updated weekend additions during May event weekends.

To score cheap flights from Ontario International Airport (ONT) to San Francisco International Airport (SFO) in May, search 2–6 weeks before travel and target midweek departures (Tuesdays, Wednesdays). Use flexible dates and set fare alerts; compare low-cost carriers and legacy airlines for bundled perks versus base fare savings. Consider early-morning flights to increase on-time rates and lower prices. Leverage loyalty points or companion pass promotions from Alaska or Southwest and check for flash sales during off-peak hours. CTA: Compare fares across flight search engines and book early to lock in the best May deals between ONT and SFO.