Cheap flights from San Francisco to Los Angeles from $42

In general, August is the cheapest month to fly from San Francisco to Ontario. Due to it being the ‘off-season’ during this time, you can expect flight prices to be around $171. If you aren’t able to travel during the month of August, then book flights to Ontario from San Francisco during June instead. Flights to Ontario in June, while not as cheap as those in August, still average around $188.

The cheapest day to depart on your flight to Ontario is on a Monday when prices can be found for as low as $167. This is often the case because there is less demand to fly during this day of the week. When flying out on a Sunday, the most expensive travel day of the week, you can expect to see flight prices from San Francisco to Ontario for around $259.

In the evening is the cheapest time of day to fly from San Francisco to Ontario when you can find flight prices for as low as $186. Flying to Ontario in the evening is an ideal time because this is during off-peak travel hours. If you have a flexible travel schedule, then try to avoid flying in the afternoon when prices are $254 on average. Flights to Ontario from San Francisco in the afternoon are generally more expensive because this time of day is more convenient for travelers’ schedules.

Fly from San Francisco to Ontario for the best San Francisco - Ontario flight prices

You are more likely to see cheaper flights to Ontario from San Francisco when booking weeks ahead of your departure date. In general, you can expect to find flights to Ontario for around $225 when searching weeks out. However, flight prices might be lower outside of this timeframe. For example, people recently found flights to Ontario from San Francisco for as low as $142 on momondo.

There are 4 cabin classes available to choose from on San Francisco to Ontario flights. Cabin price and availability will vary by airline so perform a search above to find the right deals for you.

United Airlines and Southwest are the most popular carriers operating from San Francisco to Ontario

Alaska Airlines, Southwest and Frontier are the top three most popular airlines that fly to Ontario from San Francisco according to our data. Alaska Airlines is the first choice among our users, with 28% of people opting to fly with this airline when traveling to Ontario. Keep in mind that there are 10 different airlines that fly to Ontario on a routine basis, so you have a few additional options to choose from.

Historically, on average around 16% of flights between San Francisco and Ontario have experienced a delay on any given week. The average delay length over the past 12 months has been 110 minutes.

Generally, flights departing in the evening tend to experience fewer delays. Flights at night have, in the past, seen delays more frequently in comparison.

Saturday is statistically the day of the week which experiences the fewest number of delays on this flight route. Monday has historically seen more delays on average compared to the rest of the week.

According to our data, United Airlines have had the least number of delays on this route over the last 12 months; with about 14% of their flights experiencing any sort of delay.

The number of flights available between San Francisco and Ontario is 5 per day as of October 2026. The most frequent departure time is 4:00PM, with 38% of daily flights leaving in the afternoon.

As of October 2026, there are 41 flights per week flying from San Francisco to Ontario. The most common day of the week flights depart is Thu, with 32% of flights taking off on this day.