The cheapest times to fly from CWL to SEA are

  • January 8th to May 27th (except the weeks of March 26th and April 2nd)
  • November 5th to December 2nd

based on data collected exclusively by Champion Traveler across tens of millions of flights. Among all the dates above, the very cheapest time to fly from CWL to SEA is early February. Prices can be as high as $1170 for Friday flights during mid July, or as low as $493 for Tuesday flights around early February.


When to Fly to Seattle

Flying from Cardiff (CWL) to Seattle, WA (SEA) will usually cost between $493 to $930 per person if booking more than four weeks in advance. On average the very cheapest time to fly is early February with an average ticket price of $493. Due to high demand the most expensive time to fly is mid July, with an average price of $955. Planning your trip to low-cost times can easily save you $462 on economy flights and even more on first-class flights. Generally, any price below $591 can be considered a good price for a round-trip CWL to SEA flight.

See below for a graph of average weekly prices for the CWL to SEA route. All prices are for round-trip tickets in USD.

CWL to SEA Flight Prices

Compared to other flights, the CWL to SEA flight is cheaper than the average and costs less than the average flight leaving from Cardiff. The average price per mile (for a direct flight) is $0.08, which is far below average.


Flight Prices by Day of the Week

Tuesday is usually the cheapest day to depart and return on this flight. Fridays are the most expensive days to fly to Seattle, and Saturdays are the most expensive days to return to Cardiff. Selecting flights on the least expensive days could save you up to $110 (13%) on this flight.

Departing prices are for round-trip flights returning on the day of departure. For example, a flight departing on Tuesday and returning a week later will cost an average of $581. Return trip prices are from the SEA to CWL flight, and often highlight the quality of our data in showing the same trend.

Departing Prices by Day

Departure Day Prices

Return Trip Prices by Day

Return Day Prices


Nonstop Flights and Layovers

Travelers looking to fly from CWL to SEA can generally find a 1-layover flight. Because there is not usually a direct flight option the real-world direct flight time of 9 hour 28 minutes may not be realistic.


Flight Questions Answered

Still have questions about flying from CWL to SEA? We’ve got answers.

Which airlines fly this route?

You can find 10 major airlines flying this route most often: Aer Lingus, Air France, Alaska, Alitalia, Delta, Finnair, Icelandair, KLM, Virgin Atlantic, WestJet, and potentially more during busy seasons.

How far away is it from Seattle/Tacoma International Airport to Cardiff Airport?

The distance between the two airports is roughly 4711 miles or 7582 kilometers.

How long does it take to fly from CWL to SEA?

The real-world flight time for a nonstop CWL to SEA flight is about 9 hour 28 minutes.

How many flights go between Cardiff and Seattle, WA?

It depends on the day of the week and the date, but a typical day might have around 8 available flights from CWL to SEA.


Airport Location Info


Departing Airport

Origination code CWL
Origination airport name Cardiff Airport
City Cardiff
Country the United Kingdom
Latitude 51.4
Longitude -3.3

Return Airport

Destination code SEA
Destination airport name Seattle/Tacoma International Airport
City Seattle, WA
Country the United States
Latitude 47.5
Longitude -122.3


Other Resources

Please note that while we’ve worked hard to analyzed tens of millions of flights to get you this data, we do not calculate current live prices or guarantee pricing. Please see our partners using the links above for current offers.