Cheap flights from the United States to Ontario from $27

In general, September is the cheapest month to fly from United States to Ontario. Due to it being the ‘off-season’ during this time, you can expect flight prices to be around $287. If you aren’t able to travel during the month of September, then book flights to Ontario from United States during October instead. Flights to Ontario in October, while not as cheap as those in September, still average around $287.

The cheapest day to depart on your flight to Ontario is on a Friday when prices can be found for as low as $307. This is often the case because there is less demand to fly during this day of the week. When flying out on a Monday, the most expensive travel day of the week, you can expect to see flight prices from United States to Ontario for around $387.

In the evening is the cheapest time of day to fly from United States to Ontario when you can find flight prices for as low as $329. 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 $337 on average. Flights to Ontario from United States in the afternoon are generally more expensive because this time of day is more convenient for travelers’ schedules.

Fly from Las Vegas Harry Reid Intl to Ontario for the best United States - Ontario flight prices

You are more likely to see cheaper flights to Ontario from United States when booking weeks ahead of your departure date. In general, you can expect to find flights to Ontario for around $353 when searching weeks out. However, flight prices might be lower outside of this timeframe. For example, people recently found flights to Ontario from United States for as low as $268 on momondo.

There are 4 cabin classes available to choose from on United States 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, Southwest, and Frontier are the most popular carriers operating from United States to Ontario

Frontier, American Airlines and United Airlines are the top three most popular airlines that fly to Ontario from United States according to our data. Frontier is the first choice among our users, with 33% of people opting to fly with this airline when traveling to Ontario. Keep in mind that there are 12 different airlines that fly to Ontario on a routine basis, so you have a few additional options to choose from.

Historically, on average around 17% of flights between United States and Ontario have experienced a delay on any given week. The average delay length over the past 12 months has been 122 minutes.

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

Tuesday 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 13% of their flights experiencing any sort of delay.

The number of flights available between United States and Ontario is 21 per day as of March 2026. The most frequent departure time is 7:00PM, with 47% of daily flights leaving in the evening.

147 flights are operational weekly from United States to Ontario as of March 2026. The most popular departure day for this route is Fri, with 39% of flights per week taking off on this day.