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Cheap flights from Washington, D.C. Dulles Intl Airport to Seattle from £106

This is the cheapest one-way flight price found by a Cheapflights user in the last 72 hours by searching for a flight departing on 15/11. Fares are subject to change and may not be available on all flights or dates of travel.
IAD — SEA
18 Jun — 25 Jun1
1 adult

Cheap flight deals from Dulles Intl to Seattle

Discover tips and strategies to find the most affordable flight options for your journey from Dulles Intl (IAD) to Seattle (SEA). Learn about various techniques such as flexible date searches, comparing prices across and setting up price alerts. Use these methods to find the cheapest flights available for your travel needs. Data last updated 13 June 2025.

Round-trip from

£196

One-way from

£106

Popular in

December

Cheapest in

February

Average price

£351
Alaska Airlines
  • Alaska Airlines
  • 12/8-12/8
  • 1 total stop
  • 34h 05m total
  • Washington, D.C. to Seattle
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United Airlines
  • United Airlines
  • 15/11
  • 1 total stop
  • 9h 30m total
  • Washington, D.C. to Seattle
Search Deals
Highest demand for flights based on searches. 2% potential increase in price (£4 potential increase over avg. return price).
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Cheapest flight prices on average. 2% potential price decrease (£6 potential savings vs. average return price).
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Average for round-trip flights in June 2025
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Find flight deals from Dulles Intl to Seattle

Cheapest flights from Dulles Intl to Seattle
Explore the most affordable flight options available from Dulles Intl to Seattle. Find the lowest fares from popular airlines and budget airlines, with prices last updated on 13 June 2025.

Tue 12/806:30IAD - SEA
Nonstop5h 47mAlaska Airlines
Tue 12/811:41SEA - IAD
1 stop28h 18mAlaska Airlines
Deal found 11/6£196
Sat 20/913:05IAD - SEA
Nonstop5h 46mUnited Airlines
Sat 20/922:55SEA - IAD
Nonstop5h 03mUnited Airlines
Deal found 12/6£204
Sat 19/712:46IAD - SEA
1 stop13h 01mSun Country Air
Tue 22/718:21SEA - IAD
1 stop14h 22mSun Country Air
Deal found 12/6£217
Sat 30/817:05IAD - SEA
1 stop7h 40mSouthwest
Thu 4/905:00SEA - IAD
1 stop10h 15mSouthwest
Deal found 11/6£222
Sun 7/907:00IAD - SEA
Nonstop5h 40mHawaiian Airlines
Sun 14/923:30SEA - IAD
Nonstop5h 02mHawaiian Airlines
Deal found 12/6£233
Wed 23/707:30IAD - SEA
Nonstop5h 47mDelta
Tue 29/721:55SEA - IAD
Nonstop5h 02mDelta
Deal found 12/6£263

Cheapflights Fare Finder

Customise your flight search to find flights from Dulles Intl to Seattle that fit within your specific budget. Explore options based on user searches and filter the results based on your desired price range. Find flights that match your budget for a cost-effective journey. Over the last 7 days, Cheapflights users made 858,174 searches. Data last updated 13 June 2025.
Use the filters below to find and compare flights from Washington, D.C. Dulles Intl Airport to Seattle that are best for you.

Fly from

Dulles Intl

Fly to

Seattle

Route

Depart

Return

Price

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Tue 12/8

06:30-09:17

Nonstop5h 47m

Seattle/Tacoma Intl

Tue 12/8

11:41-18:59

1 stop28h 18m

£196

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Sat 20/9

13:05-15:51

Nonstop5h 46m

Seattle/Tacoma Intl

Sat 20/9

22:55-06:58

Nonstop5h 03m

£204

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Sat 19/7

12:46-22:47

1 stop13h 01m

Seattle/Tacoma Intl

Tue 22/7

18:21-11:43

1 stop14h 22m

£217

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Sat 30/8

17:05-21:45

1 stop7h 40m

Seattle/Tacoma Intl

Thu 4/9

05:00-18:15

1 stop10h 15m

£222

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Sun 7/9

07:00-09:40

Nonstop5h 40m

Seattle/Tacoma Intl

Sun 14/9

23:30-07:32

Nonstop5h 02m

£233

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Wed 23/7

07:30-10:17

Nonstop5h 47m

Seattle/Tacoma Intl

Tue 29/7

21:55-05:57

Nonstop5h 02m

£263

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Sat 15/11

12:55-19:25

1 stop9h 30m

£106

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Wed 13/8

17:25-23:44

1 stop9h 19m

£109

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Sun 10/8

07:30-10:17

Nonstop5h 47m

£110

Washington, D.C.Seattle

IAD - SEA

IADSEA

Washington, D.C. Dulles Intl

Fri 3/10

18:30-17:01

1 stop25h 31m

£113

Flights are sorted by cheapest return flights first.

Deals found on 11/6

Showing 1-10 of 13 results
1
2

Best time to book a flight from Dulles Intl to Seattle

Have a flexible travel schedule? Discover the best time to fly to Seattle from Dulles Intl with our price prediction graph.
Estimated return price
Rates are based on past data. Find the cheapest month and day to book your flight based on your travel requirements, then search for cheap deals.

Cheapflights Insights

Everything you need to know about your flight from Washington, D.C. Dulles Intl Airport to Seattle

How far ahead should I book a flight from Washington, D.C. Dulles Intl Airport to Seattle?

Use this chart to determine the optimal time to book a return flight from Dulles Intl to Seattle. Price data was last updated on 9 June 2025.

The best time to book flights from Washington, D.C. Dulles Intl Airport to Seattle is 66 days before your desired departure date. The cost of your flight will likely increase significantly if you book two weeks in advance of your flight.

What is the cheapest month to book a flight from Washington, D.C. Dulles Intl Airport to Seattle?

Currently, January is the cheapest month in which you can book a flight from Washington, D.C. Dulles Intl Airport to Seattle (average of £622). Flying from Washington, D.C. Dulles Intl Airport to Seattle in July is currently the most expensive (average of £946). There are several factors that can impact the price of a flight, so comparing airlines, departure airports and flight times can provide users with more options.

What is the cheapest time of day to fly from IAD to SEA?

Find hourly flight availability from Dulles Intl to Seattle. Discover flight options and departure times throughout the day, allowing you to choose a departure time that suits your schedule. Data last updated 13 June 2025.

When flying from Washington, D.C. Dulles Intl Airport to Seattle, the time of day you fly usually plays a role in the price. Save by searching for a flight at midday, which can drop the price by up to 20% versus a flight in the morning.

Weekly flight availability from Washington, D.C. Dulles Intl Airport to Seattle

Explore weekly flight availability from Dulles Intl to Seattle. Discover flights operating on different days of the week, giving you the flexibility to choose a travel day that best fits your plans. Compare info to find the most convenient option for your journey. Data last updated 13 June 2025.

The most flights from IAD to SEA are scheduled on a Thursday (30 on average). You will have fewer flight options on Saturday, which is when the least amount of flights are scheduled (9 on average).

Rainfall in Seattle by month

Plan your trip to Seattle by taking into account the average rainfall totals by month.

In terms of precipitation, rainfall in Seattle ranges from 18.0 - 168.0 inches per month. November is typically the wettest month, when rainfall can reach 168.0 mm. July is typically the driest time to visit Seattle when rainfall is around 18.0 mm.

Temperature in Seattle by month

Plan your trip to Seattle by taking into account the average temperature totals by month.

If weather is an important factor for your trip to Seattle, use this chart to help with planning. For those seeking warmer temperatures, July is the ideal time of year to visit, when temperatures reach an average of 19.0 C. Travellers hoping to avoid the cold should look outside of December, when temperatures are typically at their lowest (around 5.0 C).

Reviews of airlines servicing Seattle

Get insights into the airlines that provide service to Seattle. Read reviews, discover amenities, and learn about the overall travel experience offered by airlines. Use this information to make informed decisions when choosing an airline for your flight to Seattle. Reviews last updated 13 June 2025.
See what other customers who have flown with Alaska Airlines, Southwest and Delta from Washington, D.C. to Seattle have to say. You can also see how each airline stacks up in terms of entertainment options, comfort, food, crew/service, and boarding process.
Alaska Airlines
8.0
Very Good
10,000 reviews
Check prices

Food

7.1

Entertainment

7.1

Overall

8.0

Boarding

8.1

Comfort

7.8

Crew

8.5

Reviews

1 / 20
10.0
Excellent

Cheri,Jan 2025

FAT - SEA

Very friendly. I really liked that they had water for us in cartons not plastic. Impressed with Alaska Airlines, First time I had flown them
Alaska Airlines
8.0
Very Good
10,000 reviews
Alaska Airlines
8.0
Very Good
10,000 reviews
Check prices

Food

7.1

Entertainment

7.1

Overall

8.0

Boarding

8.1

Comfort

7.8

Crew

8.5

Reviews

1 / 20
10.0
Excellent

Cheri,Jan 2025

FAT - SEA

Very friendly. I really liked that they had water for us in cartons not plastic. Impressed with Alaska Airlines, First time I had flown them
Southwest
8.0
Very Good
4,287 reviews
Alaska Airlines
8.0
Very Good
10,000 reviews
Check prices

Food

7.1

Entertainment

7.1

Overall

8.0

Boarding

8.1

Comfort

7.8

Crew

8.5

Reviews

1 / 20
10.0
Excellent

Cheri,Jan 2025

FAT - SEA

Very friendly. I really liked that they had water for us in cartons not plastic. Impressed with Alaska Airlines, First time I had flown them
Delta
8.0
Very Good
7,950 reviews
Alaska Airlines
8.0
Very Good
10,000 reviews
Check prices

Food

7.1

Entertainment

7.1

Overall

8.0

Boarding

8.1

Comfort

7.8

Crew

8.5

Reviews

1 / 20
10.0
Excellent

Cheri,Jan 2025

FAT - SEA

Very friendly. I really liked that they had water for us in cartons not plastic. Impressed with Alaska Airlines, First time I had flown them
Hawaiian Airlines
7.9
Good
2,494 reviews
Alaska Airlines
8.0
Very Good
10,000 reviews
Check prices

Food

7.1

Entertainment

7.1

Overall

8.0

Boarding

8.1

Comfort

7.8

Crew

8.5

Reviews

1 / 20
10.0
Excellent

Cheri,Jan 2025

FAT - SEA

Very friendly. I really liked that they had water for us in cartons not plastic. Impressed with Alaska Airlines, First time I had flown them
United Airlines
7.4
Good
8,790 reviews
Alaska Airlines
8.0
Very Good
10,000 reviews
Check prices

Food

7.1

Entertainment

7.1

Overall

8.0

Boarding

8.1

Comfort

7.8

Crew

8.5

Reviews

1 / 20
10.0
Excellent

Cheri,Jan 2025

FAT - SEA

Very friendly. I really liked that they had water for us in cartons not plastic. Impressed with Alaska Airlines, First time I had flown them

Related info for your journey

Find useful and relevant information for your journey from Dulles Intl to Seattle. Access travel guides, tips, and recommendations to enhance your travel experience. Get information about local attractions, weather, transportation options, and more.

  • What airport do you fly into for flights to Seattle from Washington, D.C. Dulles Intl?

    Located just 11.4 mi from the city center, Seattle/Tacoma Intl is the airport most travelers will use when flying to Seattle from Washington, D.C. Dulles Intl. Booking flights from Washington, D.C. Dulles Intl to Seattle/Tacoma Intl (SEA) should be relatively easy as there are 21 daily inbound flights from Washington, D.C. Dulles Intl from 0 different airlines.

  • What are the cheapest airlines flying from Washington, D.C. Dulles Intl Airport to Seattle round-trip?

    Our cheapest airline available from Washington, D.C. Dulles Intl Airport to Seattle is Alaska Airlines. Our recent data shows that you can find tickets from as low as £196 on this airline. Additional options worth looking into are United Airlines and Sun Country Air, starting at £208 and £217 round-trip. Alaska Airlines is 35% cheaper than the average price of flights available within the next 90 days to this destination.

  • What are the cheapest airlines to fly from Washington, D.C. Dulles Intl Airport to Seattle one-way?

    The cheapest airline one-way is United Airlines, with whom users have recently found tickets for as low as £106. However, be on the lookout for offers from Hawaiian Airlines and Delta, as they are both options that can get you from Washington, D.C. Dulles Intl Airport to Seattle for a low price.

  • What are the most reliable airlines from Washington, D.C. Dulles Intl Airport to Seattle?

    The top 3 most reliable airlines when flying from Washington, D.C. Dulles Intl Airport to Seattle are Japan Airlines (97%), China Eastern (90%) and Delta (90%).

  • Can I find deals for flights from Dulles Intl to Seattle that include hotel bookings?

    Yes. In addition to deals on Dulles Intl to Seattle flights, Cheapflights offers holiday packages that include both flights and hotel.

  • How can I find direct flights from Dulles Intl to Seattle?

    After entering your origin and destination, apply the non-stop filter on the search result page to find direct flights from Dulles Intl to Seattle.

  • Can I find deals for business class flights from Dulles Intl to Seattle?

    Yes. Cheapflights offers flight deals from Dulles Intl to Seattle by cabin class. In addition to browsing deals, you can also filter by cabin class on the search results page after making a search.

  • What is the cheapest month to book a flight from Washington, D.C. Dulles Intl Airport to Seattle?

    Currently, January is the cheapest month in which you can book a flight from Washington, D.C. Dulles Intl Airport to Seattle (average of £622). Flying from Washington, D.C. Dulles Intl Airport to Seattle in July is currently the most expensive (average of £946). There are several factors that can impact the price of a flight, so comparing airlines, departure airports and flight times can provide users with more options.

See more FAQs

Travelling to a place near Washington, D.C. Dulles Intl Airport?

Book flights to Washington, D.C. Dulles Intl Airport if you plan to visit one of these locations
Tacoma
Leavenworth
Bothell

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Can Cheapflights find flights from Dulles Intl to Seattle with no change fees?

Need flexible booking options for your flight to Seattle from Dulles Intl? Don’t worry, Cheapflights have you covered. Use our search filter to only show flights with no change fees.

Can Cheapflights notify me if prices for flights from Dulles Intl to Seattle become cheaper?

Yes, Cheapflights offers price alerts on Dulles Intl to Seattle flights so you can book your travel at the perfect time. Price Alerts can be enabled by clicking the bell icon next to the flight deals above and providing your email address where you want to receive the alerts.

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