Cheap flights from Ontario to the United States from $21

In general, January is the cheapest month to fly from Ontario to United States. Due to it being the ‘off-season’ during this time, you can expect flight prices to be around $315. If you aren’t able to travel during the month of January, then book flights to United States from Ontario during February instead. Flights to United States in February, while not as cheap as those in January, still average around $321.

According to our data, Tuesday is the cheapest day to fly to United States from Ontario. The lowest ticket price found for a Tuesday departure recently was $428. Keep in mind that prices can always vary depending on your route and whether or not you are flying domestic or international. If your travel schedule is flexible, try to avoid departing on a Saturday because tickets tend to average around $488. These prices are subject to change though, so be sure to set up a Price Alert for flights to United States.

The cheapest time of day to fly to United States is in the morning when flights can be purchased for as low as $452. Try not to purchase tickets in the evening because they tend to be around $454. Of course, these prices can vary depending on the time of year and what airport you fly to.

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

You are more likely to see cheaper flights to United States from Ontario when booking weeks ahead of your departure date. In general, you can expect to find flights to United States for around $403 when searching weeks out. However, flight prices might be lower outside of this timeframe. For example, people recently found flights to United States from Ontario for as low as $270 on momondo.

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

Frontier, Southwest, and Alaska Airlines are the most popular carriers operating from Ontario to United States

American Airlines, United Airlines and Frontier are the top three most popular airlines that fly to United States from Ontario according to our data. American Airlines is the first choice among our users, with 29% of people opting to fly with this airline when traveling to United States. Keep in mind that there are 9 different airlines that fly to United States on a routine basis, so you have a few additional options to choose from.

Historically, on average around 13% of flights between Ontario and United States have experienced a delay on any given week. The average delay length over the past 12 months has been 125 minutes.

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

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

According to our data, Delta have had the least number of delays on this route over the last 12 months; with about 6% of their flights experiencing any sort of delay.

As of November 2026, there are 43 flights per day flying from Ontario to United States. The most common time of day flights depart is 7:00AM, with 48% of flights taking off at noon.

As of November 2026, there are 304 flights per week flying from Ontario to United States. The most common day of the week flights depart is Wed, with 26% of flights taking off on this day.