Cheap flights from Ontario to Seattle from $133 ONT → SEA

Found recently, and the cheapest we hold

What have prices looked like?

Over 49 days, 24 Sept to 11 Nov, the cheapest return we saw each day was $96 to $216.

At $228, the cheapest return found recently is above that range.

Those were the prices on those days, not today's.

Could nearby dates be cheaper?

We hold no other 7-night return fares leaving within 3 days of 11 Dec to compare.

Every date we hold

62 fares on 16 departure dates

Which month looks cheapest?

December 2026 is the cheapest month — from $216.

Found recently, and the cheapest we hold

What have prices looked like?

Over 47 days, 24 Sept to 11 Nov, the cheapest one-way we saw each day was $44 to $178.

Those were the prices on those days, not today's.

Could nearby dates be cheaper?

We hold no other one-way fares leaving within 3 days of 17 Jul 2027 to compare.

Every date we hold

5 fares on 5 departure dates

Which month looks cheapest?

February 2027 is the cheapest month — from $109.

Return

Fares 30 to 59 days before departure were typically 53% lower than 0 to 6 days before departure.

From the cheapest return each day between 24 Sept and 11 Nov (49 days), grouped by how many days ahead the flight left; one adult in economy.

Each range covers different departure dates, so this compares typical fares, not the same trip priced twice.

Prices reflect recent searches — current fares may differ.

One-way

Fares 14 to 29 days before departure were typically 25% lower than 0 to 6 days before departure.

From the cheapest one-way each day between 24 Sept and 11 Nov (47 days), grouped by how many days ahead the flight left; one adult in economy.

Each range covers different departure dates, so this compares typical fares, not the same trip priced twice.

Prices reflect recent searches — current fares may differ.

How much is a return flight from Ontario to Seattle?

The cheapest return found recently is $228 with Alaska Airlines, 11 Dec to 18 Dec, found 2 days ago. The cheapest return we hold, of any age, is $216 with Frontier Airlines, 8 Dec to 11 Dec, found 5 days ago. The cheapest return fare on each of 16 departure dates is usually $242 to $270.

How much is a one-way flight from Ontario to Seattle?

The cheapest one-way found recently is $133 with Alaska Airlines, 17 Jul 2027, found 2 days ago. The cheapest one-way we hold, of any age, is $109 with Frontier Airlines, 24 Feb 2027, found 4 days ago. The cheapest one-way fare on each of 5 departure dates is usually $118 to $133.

What is the cheapest month to fly from Ontario to Seattle?

December 2026 is the cheapest month for a return, from $216, 8 Dec to 11 Dec, found 5 days ago. February 2027 is the cheapest month for a one-way, from $109, 24 Feb 2027, found 4 days ago.

How far ahead should I book a flight from Ontario to Seattle?

In 49 days of prices between 24 Sept and 11 Nov, return fares 30 to 59 days before departure were typically 53% lower than 0 to 6 days before departure. In 47 days of prices between 24 Sept and 11 Nov, one-way fares 14 to 29 days before departure were typically 25% lower than 0 to 6 days before departure.

Is there a direct flight from Ontario to Seattle?

Yes, the cheapest nonstop return found recently is $228 with Alaska Airlines, 11 Dec to 18 Dec, found 2 days ago.

Every nonstop date from Ontario to Seattle

How long is the flight from Ontario to Seattle?

The cheapest one-way found recently, with Alaska Airlines on 17 Jul 2027, takes 4 h 35 min with 1 stop.

Which airlines have the cheapest flights from Ontario to Seattle?

Between 20 Nov and 11 Jun 2027, Frontier Airlines has the cheapest return on 8 of the 16 departure dates we hold, and Alaska Airlines on 8. Between 11 Dec and 17 Jul 2027, Frontier Airlines has the cheapest one-way on 3 of the 5 departure dates we hold, and Alaska Airlines on 2.