Cheap flights from Seattle to London from £342

In general, January is the cheapest month to fly from Seattle to London Heathrow Airport. Due to it being the ‘off-season’ during this time, you can expect flight prices to be around £471. The month of October is another great option to travel to London Heathrow Airport, with average flight prices from Seattle averaging around £491.

On average, the least expensive day to fly to London Heathrow Airport from Seattle is on a Tuesday. momondo users have found tickets for Tuesday departures for as low as £504. However, this price may fluctuate depending on the airline, the season, and holidays. Be sure to avoid booking your departure on a Monday as prices are generally higher than usual. According to our data, the average ticket price to London Heathrow Airport on Monday is £644.

According to our data, the cheapest time of day to fly to London Heathrow Airport is at midday. momondo users have found flights departing from Seattle to London Heathrow Airport at midday for as low as £571. Keep in mind that these prices may fluctuate based on what airline you choose and the time of year you plan to travel. If you have a flexible travel schedule, then try to avoid flying in the afternoon when prices are £606 on average. Flights to London Heathrow Airport from Seattle in the afternoon are generally more expensive because this time of day is more convenient for travellers’ schedules.

Fly from Seattle/Tacoma Intl to London Heathrow for the best Seattle/Tacoma Intl - London Heathrow flight prices

You are more likely to see cheaper flights to London Heathrow Airport from Seattle when booking weeks ahead of your departure date. In general, you can expect to find flights to London Heathrow Airport for around £604 when searching weeks before you fly. However, flight prices might be lower outside of this timeframe. For example, people recently found flights to London Heathrow Airport from Seattle for as low as £533 on momondo.

You could potentially save up to 12% on your flight if you consider stops on a Seattle to London Heathrow Airport flight.

As of May 2026, prices for Seattle to London Heathrow Airport flights are approximately 55% more expensive when compared to flights at the same time last year.

Historically, on average around 14% of flights between Seattle and London have experienced a delay on any given week. The average delay length over the past 12 months has been 128 minutes.

Generally, flights departing at night tend to experience fewer delays. Flights departing in the evening have, in the past, seen delays more frequently in comparison.

Tuesday is statistically the day of the week that experiences the fewest delays on this flight route. Wednesday has historically seen more delays on average compared to the rest of the week.

According to our data, Virgin Atlantic have had the fewest delays on this route over the last 12 months, with about 6% of their flights experiencing any sort of delay.

As of May 2026, 21 flights take off from Seattle and land in London Heathrow Airport each day. The most common flight departure time for this route is 13:00, with 71% of daily flights taking off in the evening.

147 flights are operational weekly from Seattle to London Heathrow Airport as of May 2026. The most popular departure day for this route is Tue, with 15% of flights per week taking off on this day.