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Nonstop flights from Ontario to Seattle from $228 ONT → SEA

Ontario International Airport (ONT) → Seattle-Tacoma International Airport (SEA)

The cheapest nonstop return found recently is $228 with Alaska Airlines, 11 Dec – 18 Dec, found 2 days ago.

Nonstop return

The cheapest nonstop return fare on each of 9 departure dates is usually $240 to $261.

Cheapest nonstop return

$228

11 Dec – 18 Dec · Alaska Airlines

Ontario International Airport (ONT) → Seattle-Tacoma International Airport (SEA)

Leaves 5:01 p.m. · Return leaves 7:05 a.m. · 5 h 44 min of travel, both ways together

out nonstop, back nonstop

found 2 days ago

See prices for these datesCheck today's price

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Airlines flying it nonstop on the return fares we hold: Alaska Airlines (9 departure dates), Frontier Airlines (2 departure dates), Southwest Airlines (2 departure dates).

On the 5 trips where we hold both on the same dates, nonstop cost a median $73 (24.2%) less than the cheapest fare with stops. Nonstop was cheaper or the same price on 3 of those 5 trips.

Every nonstop date we hold

Nonstop fares on 9 of the 16 departure dates we hold for this route.

30 Nov – 2 Dec: $218, found 6 days ago4 Dec – 11 Dec: $261, found 5 days ago11 Dec – 18 Dec: $228, found 2 days ago23 Dec – 1 Jan 2027: $240, found 2 days ago26 Dec – 29 Dec: $391, found 5 days ago19 Jan 2027 – 22 Jan 2027: $312, found 4 days ago2 Feb 2027 – 15 Feb 2027: $258, found 3 days ago2 Jun 2027 – 11 Jul 2027: $257, found 3 days ago11 Jun 2027 – 15 Jun 2027: $259, found 3 days agoNovDecJanFebJun
See the chart as a table
The cheapest price seen for each departure date — per traveler in Economy.
DatesFromAirlineAirportsStopsFound
30 Nov – 2 Dec$218Frontier AirlinesOntario International Airport (ONT) → Seattle-Tacoma International Airport (SEA)out nonstop, back nonstopfound 6 days agoSee prices for these dates
4 Dec – 11 Dec$261Alaska AirlinesOntario International Airport (ONT) → Seattle-Tacoma International Airport (SEA)out nonstop, back nonstopfound 5 days agoSee prices for these dates
11 Dec – 18 Dec$228Alaska AirlinesOntario International Airport (ONT) → Seattle-Tacoma International Airport (SEA)out nonstop, back nonstopfound 2 days agoSee prices for these dates
23 Dec – 1 Jan 2027$240Alaska AirlinesOntario International Airport (ONT) → Seattle-Tacoma International Airport (SEA)out nonstop, back nonstopfound 2 days agoSee prices for these dates
26 Dec – 29 Dec$391Alaska AirlinesOntario International Airport (ONT) → Seattle-Tacoma International Airport (SEA)out nonstop, back nonstopfound 5 days agoSee prices for these dates
19 Jan 2027 – 22 Jan 2027$312Alaska AirlinesOntario International Airport (ONT) → Seattle-Tacoma International Airport (SEA)out nonstop, back nonstopfound 4 days agoSee prices for these dates
2 Feb 2027 – 15 Feb 2027$258Alaska AirlinesOntario International Airport (ONT) → Seattle-Tacoma International Airport (SEA)out nonstop, back nonstopfound 3 days agoSee prices for these dates
2 Jun 2027 – 11 Jul 2027$257Alaska AirlinesOntario International Airport (ONT) → Seattle-Tacoma International Airport (SEA)out nonstop, back nonstopfound 3 days agoSee prices for these dates
11 Jun 2027 – 15 Jun 2027$259Alaska AirlinesOntario International Airport (ONT) → Seattle-Tacoma International Airport (SEA)out nonstop, back nonstopfound 3 days agoSee prices for these dates

Prices are what travelers' searches on Aviasales found in the last 7 days, in US dollars: the price the seller showed on Aviasales; bags may cost extra. Fares change, so check today's price before you book. How our prices work