Ontario to Seattle ONT → SEA
Ontario International Airport (ONT) → Seattle-Tacoma International Airport (SEA)
The cheapest return found recently is $258 with Alaska Airlines, 4 Dec – 6 Dec, found today. The cheapest one-way found recently is $73 with Frontier Airlines, 21 Nov, found yesterday.
Return
The cheapest return fare on each of 10 departure dates is usually $201 to $276.
Cheapest return found recently
$258
4 Dec – 6 Dec · Alaska Airlines
Ontario International Airport (ONT) → Seattle-Tacoma International Airport (SEA)
Leaves 5:01 p.m. · Return leaves 1:36 p.m. · 5 h 34 min of travel, both ways together
out nonstop, back nonstop
found today
Cheapest nonstop return
$258
4 Dec – 6 Dec · Alaska Airlines
Ontario International Airport (ONT) → Seattle-Tacoma International Airport (SEA)
Leaves 5:01 p.m. · Return leaves 1:36 p.m. · 5 h 34 min of travel, both ways together
out nonstop, back nonstop
found today
Found recently, and the cheapest we hold
$258 4 Dec – 6 Decfound todaySee prices for these dates
$180 13 Nov – 23 Novfound 3 days agoSee prices for these dates
What have prices looked like?
Over 25 days, 24 Sept to 18 Oct, the cheapest return we saw each day was $96 to $198.
At $258, the cheapest return found recently is above that range.
25 days is a short history, so treat this range as an early guide.
Those were the prices on those days, not today's.
Is this a good return price?
Compared with the cheapest return fare on each of 10 departure dates from 23 Oct to 4 Dec, found by travelers' searches in the last 7 days (economy, the price the seller showed on Aviasales). The usual range is the middle half of those prices.
Could nearby dates be cheaper?
We hold no other 2-night return fares leaving within 3 days of 4 Dec to compare.
Every date we hold
11 fares on 10 departure dates
See the chart as a table
| Dates | From | Airline | Airports | Stops | Found | |
|---|---|---|---|---|---|---|
| 23 Oct – 24 Oct | $343 | Frontier Airlines | Ontario International Airport (ONT) → Seattle-Tacoma International Airport (SEA) | out 1 stop, back nonstop | found 3 days ago | See prices for these dates |
| 26 Oct – 29 Oct | $198 | Frontier Airlines | Ontario International Airport (ONT) → Seattle-Tacoma International Airport (SEA) | out nonstop, back nonstop | found 4 days ago | See prices for these dates |
| 27 Oct – 30 Oct | $290 | Frontier Airlines | Ontario International Airport (ONT) → Seattle-Tacoma International Airport (SEA) | out 1 stop, back nonstop | found yesterday | See prices for these dates |
| 1 Nov – 7 Nov | $282 | Alaska Airlines | Ontario International Airport (ONT) → Seattle-Tacoma International Airport (SEA) | out nonstop, back nonstop | found 6 days ago | See prices for these dates |
| 12 Nov – 24 Nov | $210 | Frontier Airlines | Ontario International Airport (ONT) → Seattle-Tacoma International Airport (SEA) | out 1 stop, back nonstop | found 2 days ago | See prices for these dates |
| 13 Nov – 23 Nov | $180 | Frontier Airlines | Ontario International Airport (ONT) → Seattle-Tacoma International Airport (SEA) | out nonstop, back nonstop | found 3 days ago | See prices for these dates |
| 20 Nov – 22 Nov | $184 | Frontier Airlines | Ontario International Airport (ONT) → Seattle-Tacoma International Airport (SEA) | out nonstop, back nonstop | found 3 days ago | See prices for these dates |
| 21 Nov – 22 Nov | $211 | Frontier Airlines | Ontario International Airport (ONT) → Seattle-Tacoma International Airport (SEA) | out nonstop, back nonstop | found 3 days ago | See prices for these dates |
| 3 Dec – 11 Dec | $212 | Frontier Airlines | Ontario International Airport (ONT) → Seattle-Tacoma International Airport (SEA) | out 1 stop, back nonstop | found 2 days ago | See prices for these dates |
| 4 Dec – 6 Dec | $258 | Alaska Airlines | Ontario International Airport (ONT) → Seattle-Tacoma International Airport (SEA) | out nonstop, back nonstop | found today | See prices for these dates |
Which month looks cheapest?
November 2026 is the cheapest month — from $180.
Airlines on the cheapest dates: Frontier Airlines, Alaska Airlines.
One-way
The cheapest one-way fare on each of 7 departure dates is usually $91 to $116.
Cheapest one-way found recently
$73
21 Nov · Frontier Airlines
Ontario International Airport (ONT) → Seattle-Tacoma International Airport (SEA)
Leaves 6:00 a.m. · 3 h 3 min trip
nonstop
found yesterday
Cheapest nonstop one-way
$73
21 Nov · Frontier Airlines
Ontario International Airport (ONT) → Seattle-Tacoma International Airport (SEA)
Leaves 6:00 a.m. · 3 h 3 min trip
nonstop
found yesterday
Found recently, and the cheapest we hold
$73 21 Novfound yesterdayOpen this trip
It is also the cheapest one-way we hold, of any age.
What have prices looked like?
Over 25 days, 24 Sept to 18 Oct, the cheapest one-way we saw each day was $44 to $144.
25 days is a short history, so treat this range as an early guide.
Those were the prices on those days, not today's.
Is this a good one-way price?
Compared with the cheapest one-way fare on each of 7 departure dates from 29 Oct to 2 Feb 2027, found by travelers' searches in the last 7 days (economy, the price the seller showed on Aviasales). The usual range is the middle half of those prices.
Could nearby dates be cheaper?
No. We hold one-way fares on 2 other departure dates within 3 days of 21 Nov, and none is cheaper.
Every date we hold
9 fares on 7 departure dates
See the chart as a table
| Dates | From | Airline | Airports | Stops | Found | |
|---|---|---|---|---|---|---|
| 29 Oct | $108 | Frontier Airlines | Ontario International Airport (ONT) → Seattle-Tacoma International Airport (SEA) | nonstop | found 6 days ago | Open this trip |
| 7 Nov | $105 | Frontier Airlines | Ontario International Airport (ONT) → Seattle-Tacoma International Airport (SEA) | 1 stop | found 3 days ago | Open this trip |
| 21 Nov | $73 | Frontier Airlines | Ontario International Airport (ONT) → Seattle-Tacoma International Airport (SEA) | nonstop | found yesterday | Open this trip |
| 23 Nov | $99 | Frontier Airlines | Ontario International Airport (ONT) → Seattle-Tacoma International Airport (SEA) | nonstop | found 3 days ago | Open this trip |
| 24 Nov | $83 | Frontier Airlines | Ontario International Airport (ONT) → Seattle-Tacoma International Airport (SEA) | nonstop | found 3 days ago | Open this trip |
| 12 Dec | $124 | Frontier Airlines | Ontario International Airport (ONT) → Seattle-Tacoma International Airport (SEA) | 1 stop | found 4 days ago | Open this trip |
| 2 Feb 2027 | $143 | Southwest Airlines | Ontario International Airport (ONT) → Seattle-Tacoma International Airport (SEA) | nonstop | found yesterday | Open this trip |
Which month looks cheapest?
November 2026 is the cheapest month — from $73.
Airlines on the cheapest dates: Frontier Airlines, Southwest Airlines.
Premium cabin fares from Ontario to Seattle
We hold no premium economy, business or first-class fares for this route: we collect them for the busiest routes, and this one is not among them yet.
Today's prices for 4 Dec – 6 Dec in another cabin: Premium economy · Business · First
Today's prices for 21 Nov in another cabin: Premium economy · Business · First
How far ahead were prices cheapest for Ontario to Seattle?
Return
Fares 30 to 59 days before departure were typically 62% lower than 0 to 6 days before departure.
From the cheapest return each day between 24 Sept and 18 Oct (25 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.
See these ranges as a table
| Booked ahead by | Typical fare | Cheapest day | Above the cheapest | Days of prices |
|---|---|---|---|---|
| 0–6 days | $367 | $248 | +160% | 19 |
| 7–13 days | $256 | $198 | +82% | 15 |
| 14–29 days | $193 | $96 | +37% | 25 |
| 30–59 days | $141 | $96 | Cheapest seen | 25 |
| 60–89 days | $294 | $294 | +109% | 10 |
| 90–179 days | $351 | $257 | +149% | 17 |
| 180+ days | $341 | $341 | +142% | 11 |
One-way
Fares 30 to 59 days before departure were typically 29% lower than 7 to 13 days before departure.
From the cheapest one-way each day between 24 Sept and 18 Oct (25 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.
See these ranges as a table
| Booked ahead by | Typical fare | Cheapest day | Above the cheapest | Days of prices |
|---|---|---|---|---|
| 7–13 days | $108 | $105 | +40% | 9 |
| 14–29 days | $86 | $79 | +12% | 12 |
| 30–59 days | $77 | $44 | Cheapest seen | 23 |
| 60–89 days | $140 | $91 | +82% | 12 |
| 90–179 days | $87 | $87 | +13% | 12 |
Could a nearby airport be cheaper?
A different airport at either end can change the fare — sometimes a lot.
Return
Long Beach → Seattle
60 km from Ontario
$192
$66 less than flying from Ontario
4 Dec – 6 Dec · LGB → SEA · out nonstop, back nonstop
found today
Los Angeles → Seattle
56 km from Ontario
$200
$58 less than flying from Ontario
4 Dec – 6 Dec · LAX → SEA · out 1 stop, back nonstop
found 7 hours ago
Cheapest recent price on each route — round trip, per traveler in Economy. Distances are in a straight line.
One-way
Long Beach → Seattle
60 km from Ontario
$108
$35 more than flying from Ontario
2 Feb 2027 · LGB → SEA · nonstop
found yesterday
Los Angeles → Seattle
56 km from Ontario
$123
$50 more than flying from Ontario
2 Feb 2027 · LAX → SEA · 1 stop
found 13 hours ago
Cheapest recent price on each route — one way, per traveler in Economy. Distances are in a straight line.
Live price for these dates
The cheapest return found recently is for 4 Dec – 6 Dec. A live search on this page shows what those dates cost now, for one adult in economy.
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