Cheap flights from Seattle to Ontario from $276 BFI, SEA → ONT

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 $86 to $309.

At $359, 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 0-night return fares leaving within 3 days of 26 Nov to compare.

Every date we hold

4 fares on 3 departure dates

Found recently, and the cheapest we hold

What have prices looked like?

Over 46 days, 24 Sept to 11 Nov, the cheapest one-way we saw each day was $32 to $352.

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 15 Dec to compare.

Every date we hold

11 fares on 9 departure dates

Which month looks cheapest?

January 2027 is the cheapest month — from $109.

Return

Fares 14 to 29 days before departure were typically 62% 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 78% lower than 0 to 6 days before departure.

From the cheapest one-way each day between 24 Sept and 11 Nov (46 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 Seattle to Ontario?

The cheapest return found recently is $359 with Frontier Airlines, 26 Nov to 26 Nov, found 2 days ago. The cheapest return we hold, of any age, is $270 with Frontier Airlines, 25 Nov to 30 Nov, found 4 days ago. The cheapest return fare on each of 3 departure dates is usually $315 to $414.

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

The cheapest one-way found recently is $276 with SeaPort Airlines, 15 Dec, found 2 days ago. The cheapest one-way we hold, of any age, is $109 with Frontier Airlines, 10 Jan 2027, found 6 days ago. The cheapest one-way fare on each of 9 departure dates is usually $161 to $336.

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

January 2027 is the cheapest month for a one-way, from $109, 10 Jan 2027, found 6 days ago.

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

In 49 days of prices between 24 Sept and 11 Nov, return fares 14 to 29 days before departure were typically 62% lower than 0 to 6 days before departure. In 46 days of prices between 24 Sept and 11 Nov, one-way fares 14 to 29 days before departure were typically 78% lower than 0 to 6 days before departure.

Is there a direct flight from Seattle to Ontario?

Yes, the cheapest nonstop one-way found recently is $161 with Frontier Airlines, 27 Nov, found 5 days ago.

How long is the flight from Seattle to Ontario?

The cheapest nonstop one-way found recently, with Frontier Airlines on 27 Nov, takes 2 h 48 min from Seattle-Tacoma International Airport (SEA) to Ontario International Airport (ONT). The cheapest one-way found recently, with SeaPort Airlines on 15 Dec, takes 26 h 40 min with 2 stops.

Which airlines have the cheapest flights from Seattle to Ontario?

Between 22 Nov and 26 Nov, Frontier Airlines has the cheapest return on all 3 departure dates we hold. Between 19 Nov and 10 Jan 2027, SeaPort Airlines has the cheapest one-way on 5 of the 9 departure dates we hold, and Frontier Airlines on 4.