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Cheap Flights from Washington D.C. (IAD) to Ontario (ONT)

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      Travellers and cabin class, 1 Adult, Economy

      Compare Washington Dulles to Ontario International flight deals

      Find the cheapest month or even day of the year to fly to Ontario International

      Book the best Ontario International fare with no extra fees

      Flight deals from Washington Dulles to Ontario International

      Looking for a cheap last-minute deal or the best return flight from Washington Dulles Airport to Ontario International Airport? If you want to travel next month, return fares start from $364. Find the lowest prices on one-way and return tickets right here.
      Ontario.$349 per passenger.Departing Thu, 1 Oct, returning Tue, 6 Oct.Return flight with Frontier Airlines.Outbound indirect flight with Frontier Airlines, departs from Washington Dulles on Thu, 1 Oct, arriving in Ontario International.Inbound indirect flight with Frontier Airlines, departs from Ontario International on Tue, 6 Oct, arriving in Washington Dulles.Price includes taxes and charges.From $349, select.
      Ontario.$364 per passenger.Departing Thu, 24 Sep, returning Wed, 30 Sep.Return flight with Frontier Airlines.Outbound indirect flight with Frontier Airlines, departs from Washington Dulles on Thu, 24 Sep, arriving in Ontario International.Inbound indirect flight with Frontier Airlines, departs from Ontario International on Wed, 30 Sep, arriving in Washington Dulles.Price includes taxes and charges.From $364, select.
      Ontario.$392 per passenger.Departing Sat, 26 Sep, returning Fri, 2 Oct.Return flight with Frontier Airlines.Outbound indirect flight with Frontier Airlines, departs from Washington Dulles on Sat, 26 Sep, arriving in Ontario International.Inbound indirect flight with Frontier Airlines, departs from Ontario International on Fri, 2 Oct, arriving in Washington Dulles.Price includes taxes and charges.From $392, select.
      Ontario.$446 per passenger.Departing Thu, 29 Oct, returning Mon, 2 Nov.Return flight with Frontier Airlines.Outbound indirect flight with Frontier Airlines, departs from Washington Dulles on Thu, 29 Oct, arriving in Ontario International.Inbound indirect flight with Frontier Airlines, departs from Ontario International on Mon, 2 Nov, arriving in Washington Dulles.Price includes taxes and charges.From $446, select.
      Ontario.$483 per passenger.Departing Tue, 3 Nov, returning Wed, 4 Nov.Return flight with United.Outbound indirect flight with United, departs from Washington Dulles on Tue, 3 Nov, arriving in Ontario International.Inbound indirect flight with United, departs from Ontario International on Wed, 4 Nov, arriving in Washington Dulles.Price includes taxes and charges.From $483, select.
      Ontario.$485 per passenger.Departing Tue, 16 Feb, returning Tue, 23 Feb.Return flight with Delta.Outbound indirect flight with Delta, departs from Washington Dulles on Tue, 16 Feb, arriving in Ontario International.Inbound indirect flight with Delta, departs from Ontario International on Tue, 23 Feb, arriving in Washington Dulles.Price includes taxes and charges.From $485, select.
      Ontario.$485 per passenger.Departing Tue, 15 Dec, returning Mon, 21 Dec.Return flight with United.Outbound indirect flight with United, departs from Washington Dulles on Tue, 15 Dec, arriving in Ontario International.Inbound indirect flight with United, departs from Ontario International on Mon, 21 Dec, arriving in Washington Dulles.Price includes taxes and charges.From $485, select.
      Ontario.$489 per passenger.Departing Wed, 17 Mar, returning Wed, 24 Mar.Return flight with Delta.Outbound indirect flight with Delta, departs from Washington Dulles on Wed, 17 Mar, arriving in Ontario International.Inbound indirect flight with Delta, departs from Ontario International on Wed, 24 Mar, arriving in Washington Dulles.Price includes taxes and charges.From $489, select.
      Ontario.$489 per passenger.Departing Mon, 14 Dec, returning Mon, 11 Jan.Return flight with United.Outbound indirect flight with United, departs from Washington Dulles on Mon, 14 Dec, arriving in Ontario International.Inbound indirect flight with United, departs from Ontario International on Mon, 11 Jan, arriving in Washington Dulles.Price includes taxes and charges.From $489, select.
      Ontario.$541 per passenger.Departing Fri, 8 Jan, returning Sun, 10 Jan.Return flight with United.Outbound indirect flight with United, departs from Washington Dulles on Fri, 8 Jan, arriving in Ontario International.Inbound indirect flight with United, departs from Ontario International on Sun, 10 Jan, arriving in Washington Dulles.Price includes taxes and charges.From $541, select.
      Ontario.$639 per passenger.Departing Mon, 31 Aug, returning Thu, 3 Sep.Return flight with Frontier Airlines.Outbound indirect flight with Frontier Airlines, departs from Washington Dulles on Mon, 31 Aug, arriving in Ontario International.Inbound indirect flight with Frontier Airlines, departs from Ontario International on Thu, 3 Sep, arriving in Washington Dulles.Price includes taxes and charges.From $639, select.
      Ontario.$678 per passenger.Departing Tue, 22 Jun, returning Tue, 6 Jul.Return flight with United.Outbound indirect flight with United, departs from Washington Dulles on Tue, 22 Jun, arriving in Ontario International.Inbound indirect flight with United, departs from Ontario International on Tue, 6 Jul, arriving in Washington Dulles.Price includes taxes and charges.From $678, select.
      Ontario.$900 per passenger.Departing Sun, 4 Jul, returning Wed, 7 Jul.Return flight with Alaska Airlines.Outbound indirect flight with Alaska Airlines, departs from Washington Dulles on Sun, 4 Jul, arriving in Ontario International.Inbound indirect flight with Alaska Airlines, departs from Ontario International on Wed, 7 Jul, arriving in Washington Dulles.Price includes taxes and charges.From $900, select.

      Find the cheapest month to fly from Washington Dulles to Ontario International

      We’re always keeping an eye on fares, so you can find the best one in seconds. It looks like Washington Dulles to Ontario International flights are currently cheapest in October.
      Aug
      Find prices
      Sep
      from $364
      Oct
      from $349
      Nov
      from $483
      Dec
      from $485
      Jan
      from $541
      Feb
      from $485
      Mar
      from $489
      Apr
      Find prices
      May
      Find prices
      Jun
      Find prices
      Jul
      from $900

      Washington Dulles to Ontario International: Alternative routes

      Compare routes from Washington Dulles to Ontario below. You may find an airport to fly into that's cheaper, faster, or easier than Ontario International.

      Ontario International

      4km from central Ontario
      Closest
      from $349
      Search flights

      San Bernardino Norton AFB

      39km from central Ontario
      Search flights

      Santa Ana John Wayne

      48km from central Ontario
      from $388
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      Long Beach Municipal

      54km from central Ontario
      from $410
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      Hawthorne

      65km from central Ontario
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      Burbank

      67km from central Ontario
      from $420
      Search flights

      Los Angeles International

      71km from central Ontario
      Cheapest
      from $286
      Search flights

      Washington D.C. to Ontario: Flight information

      The things to know before you go.
      Cheapest flight found$349
      Cheapest month to flyOctober

      Finding cheap flights from Washington Dulles to Ontario International: Frequently asked questions

      The best price we found for a return flight from Washington Dulles to Ontario International is $349. This is an estimate based on information collected from different airlines and travel providers over the last 4 days and is subject to change and availability.
      Currently, there are no airlines that fly direct from Washington Dulles to Ontario International. But we found flights with one or more stops from $349.
      As of August 2026, there are no flights flying from Washington Dulles to Ontario International.
      The cheapest month to fly from Washington Dulles to Ontario International is usually October.
      After crunching the numbers on our flight calendar, we found that it's currently cheapest to fly from Washington Dulles Airport to Ontario International Airport on Thursday, 1 October 2026.
      No airlines currently offer direct flights between Washington Dulles Airport and Ontario International Airport. Most routes have one or more stops.
      We show every price from over 1,200 airlines and travel agents, comparing them all so you don’t have to. If you know you want to fly to Ontario International but you’re not ready to book, set up a Price Alert. We’ll track prices for you, and let you know when they rise or fall.

      We crunched all the numbers in our flight calendar and it looks like the cheapest time to book a flight to Ontario is around 40 days in advance, so don’t leave your flight to the last minute.

      Currently, Frontier Airlines offers the cheapest flight tickets to Ontario International.

      Travelling from Washington Dulles Airport (IAD) to Ontario International Airport (ONT): what you need to know

      • Ontario's timezone is UTC-8, making Ontario three hours behind Washington DC.

      • Arriving two hours before an international flight and one hour ahead of a domestic departure are golden rules for stress-free travel. Get to the airport on time to catch your IAD to ONT flight.

      • During popular months like July, you'll want to get to the airport well in advance. Arrive two hours before domestic departures and four hours ahead for an international flight when you travel during a high season in general.

      • Consider adding a stopover when booking your ticket from Washington Dulles Airport to Ontario International Airport. Just uncheck 'Direct flights only' to break up your journey, or perhaps explore a new destination along the way. Check out these options between IAD and ONT:

        • Denver International Airport

        • Phoenix Sky Harbour Airport

        • Harry Reid International Airport

      Handy information about Washington Dulles Airport (IAD)

      • IAD is located at 1 Saarinen Circle.

      • 77% of flights that leave from Washington Dulles Airport touch down at their destination on schedule.

      • Washington Dulles Airport is about 40 kilometres from central Washington DC. If you're ride-sharing, catching a taxi or driving from the centre, it'll take 45 minutes or so to get there, depending on the traffic.

      • The trip on public transport usually takes 1 hour 10 minutes.

      • Need a convenient hotel near IAD? If you're boarding an early flight from Washington Dulles Airport to Ontario International Airport, these accommodation options will have you moments from your departure gate:

      Arriving at Ontario International Airport (ONT)

      When to fly to Ontario International Airport (ONT)

      • July is the busiest month for flights from Washington Dulles Airport to Ontario International Airport. For smaller crowds, travel to Ontario in March.

      • The warmest month in Ontario is August, with the temperature ranging between 16ºC (61ºF) and 36ºC (97ºF). Lock in your flights from Washington Dulles Airport to Ontario International Airport in this month if you like this kind of weather.

      • If you'd rather travel in cooler conditions, search for a cheap ticket from IAD to ONT in February. Average temperatures are between 4ºC (39ºF) and 24ºC (75ºF) then.

      Explore more of the United States

      • Los Angeles is just one of the many places in the United States waiting to be discovered once you've taken in the sights of Ontario. Around 56 kilometres away to the west, top sights here include Hollywood Sign, Universal Studios Hollywood and Hollywood Bowl.

      • If there's time to check out another well-known destination in the United States, head for San Diego, roughly 153 kilometres south of Ontario. San Diego Zoo, San Diego Balboa Park and USS Midway Museum are the start of reasons to visit.

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      Prices shown on this page are estimated lowest prices only. Found in the last 12 days.