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$79+ Cheap flights from Seattle (SEA) to Boulder, CO

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 8/13. Fares are subject to change and may not be available on all flights or dates of travel.
SEA — DEN
Jun 28 — Jul 51
Sat 6/28
Sat 7/5
1 adult, Economy
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Cheapflights Tip: The best prices from Seattle/Tacoma Intl to Boulder are usually found in October or September, booked 86 days in advance, depart on a Saturday or Thursday and return on a Friday

Cheap flight deals from Seattle to Boulder

Keep the following information in mind while searching for Seattle to Boulder flight deals. Data was last updated June 23, 2025.

Round-trip from

$138
(Frontier)

One-way from

$79
(Delta)

Popular in

December

Cheapest in

October

Average price

$227
From Seattle/Tacoma Intl to Boulder
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One-way flight from Seattle/Tacoma Intl to Boulder
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Highest demand for flights based on searches. 0% potential increase in price ($2 potential increase over avg. RT price).
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Cheapest flight prices on average. 2% potential price decrease ($5 potential savings vs. average RT price).
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Average for round-trip flights in June 2025
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Find flight deals from Seattle to Boulder

Cheapest flights from Seattle to Boulder
Explore the most affordable flight options available from Seattle to Boulder. Find the lowest fares from popular airlines and budget airlines, with prices last updated on June 23, 2025.

This Kiwi.com deal was found by Cheapflights users on 6/23. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 7/236:25 amSEA - DEN
Nonstop2h 49mFrontier
Mon 7/2810:29 pmDEN - SEA
Nonstop3h 05mFrontier
Deal found 6/23$137
This Orbitz deal was found by Cheapflights users on 6/23. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Orbitz is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 8/214:40 pmSEA - DEN
Nonstop2h 45mMultiple Airlines
Thu 8/289:23 pmDEN - SEA
Nonstop2h 58mMultiple Airlines
Deal found 6/23$151
This Delta deal was found by Cheapflights users on 6/23. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 11/57:35 amSEA - DEN
Nonstop2h 53mDelta
Wed 11/57:50 pmDEN - SEA
Nonstop3h 14mDelta
Deal found 6/23$157
This KAYAK deal was found by Cheapflights users on 6/21. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure KAYAK is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 10/2511:20 amSEA - DEN
1 stop5h 42mHawaiian Airlines
Mon 10/277:59 pmDEN - SEA
Nonstop3h 04mHawaiian Airlines
Deal found 6/21$163
This Alaska Airlines deal was found by Cheapflights users on 6/21. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Alaska Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 8/55:25 amSEA - DEN
1 stop4h 12mAlaska Airlines
Wed 8/138:32 pmDEN - SEA
Nonstop3h 03mAlaska Airlines
Deal found 6/21$177
This Southwest deal was found by Cheapflights users on 6/23. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 9/1611:50 amSEA - DEN
2 stops7h 00mSouthwest
Wed 9/249:15 pmDEN - SEA
Nonstop2h 55mSouthwest
Deal found 6/23$180
This American Airlines deal was found by Cheapflights users on 6/22. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 10/307:20 amSEA - DEN
1 stop8h 52mAmerican Airlines
Wed 11/58:19 amDEN - SEA
1 stop9h 40mAmerican Airlines
Deal found 6/22$190

Cheapflights Fare Finder

Customize your flight search to find flights from Seattle to Boulder 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 2,558,603 searches. Data last updated June 23, 2025.
Use the filters below to find and compare flights from Seattle to Boulder that are best for you.

Fly from

Seattle

Fly to

Boulder

Route

Depart

Return

Price

SeattleDenver

SEA - DEN

SEADEN

Seattle/Tacoma Intl

Wed 7/23

6:25 am-10:14 am

Nonstop2h 49m

Denver Intl

Mon 7/28

10:29 pm-12:34 am

Nonstop3h 05m

$137

SeattleDenver

SEA - DEN

SEADEN

Seattle/Tacoma Intl

Thu 8/21

4:40 pm-8:25 pm

Nonstop2h 45m

Denver Intl

Thu 8/28

9:23 pm-11:21 pm

Nonstop2h 58m

$151

SeattleDenver

SEA - DEN

SEADEN

Seattle/Tacoma Intl

Wed 11/5

7:35 am-11:28 am

Nonstop2h 53m

Denver Intl

Wed 11/5

7:50 pm-10:04 pm

Nonstop3h 14m

$157

SeattleDenver

SEA - DEN

SEADEN

Seattle/Tacoma Intl

Sat 10/25

11:20 am-6:02 pm

1 stop5h 42m

Denver Intl

Mon 10/27

7:59 pm-10:03 pm

Nonstop3h 04m

$163

SeattleDenver

SEA - DEN

SEADEN

Seattle/Tacoma Intl

Tue 8/5

5:25 am-10:37 am

1 stop4h 12m

Denver Intl

Wed 8/13

8:32 pm-10:35 pm

Nonstop3h 03m

$177

SeattleDenver

SEA - DEN

SEADEN

Seattle/Tacoma Intl

Tue 9/16

11:50 am-7:50 pm

2 stops7h 00m

Denver Intl

Wed 9/24

9:15 pm-11:10 pm

Nonstop2h 55m

$180

SeattleDenver

SEA - DEN

SEADEN

Seattle/Tacoma Intl

Thu 10/30

7:20 am-5:12 pm

1 stop8h 52m

Denver Intl

Wed 11/5

8:19 am-4:59 pm

1 stop9h 40m

$190

SeattleDenver

SEA - DEN

SEADEN

Seattle/Tacoma Intl

Wed 8/13

7:10 am-10:55 am

Nonstop2h 45m

$79

SeattleDenver

SEA - DEN

SEADEN

Seattle/Tacoma Intl

Sat 10/25

11:20 am-6:02 pm

1 stop5h 42m

$81

SeattleDenver

SEA - DEN

SEADEN

Seattle/Tacoma Intl

Mon 7/21

6:25 am-10:14 am

Nonstop2h 49m

$83

Flights are sorted by cheapest round-trip flights first.

Deals found on 6/22

Showing 1-10 of 16 results
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Best time to book a flight from Seattle to Boulder

Have a flexible travel schedule? Discover the best time to fly to Boulder from Seattle with our price prediction graph.
Estimated round-trip 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 Seattle to Boulder

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

Use this chart to determine the optimal time to book a round-trip flight from Seattle to Boulder. Price data was last updated on June 20, 2025.

Booking 86 days in advance of your planned departure date is, on average, the best time to get cheap flights from Seattle to Boulder. The general trend is that the closer you book to the departure date, the more expensive your flight will be.

What is the cheapest month to book a flight from Seattle to Boulder?

Currently, October is the cheapest month in which you can book a flight from Seattle to Boulder (average of $197). Flying from Seattle to Boulder in March is currently the most expensive (average of $278). 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 SEA to BD9?

Find hourly flight availability from Seattle to Boulder. Discover flight options and departure times throughout the day, allowing you to choose a departure time that suits your schedule. Data last updated June 23, 2025.

Regardless of the time of day you decide to fly, the ticket price will remain around the same. Book flights from Seattle to Boulder as you normally would.

What is the cheapest day to fly from Seattle to Boulder?

Use this chart to determine the cheapest time to fly round-trip from Seattle to Boulder. Price data was last updated on December 16, 2024.

Travelers seeking maximum savings on their Seattle to Boulder flight should consider departing on Wednesday evenings when fares are most often at their lowest. Monday mornings flights should be avoided if possible as fares are typically the most expensive at this time.

Weekly flight availability from Seattle to Boulder

Explore weekly flight availability from Seattle to Boulder. 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 June 23, 2025.

The most flights from SEA to BD9 are scheduled on a Monday (58 on average). You will have fewer flight options on Tuesday, which is when the least amount of flights are scheduled (34 on average).

Rainfall in Boulder by month

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

In terms of precipitation, rainfall in Boulder ranges from 0.5 - 2.3 inches per month. May is typically the wettest month, when rainfall can reach 2.3 in. January is typically the driest time to visit Boulder when rainfall is around 0.5 in.

Temperature in Boulder by month

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

If weather is an important factor for your trip to Boulder, 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 73.4 F. Travelers looking to avoid the cold should look outside of January, when temperatures are typically at their lowest (around 30.2 F).

Reviews of airlines servicing Boulder

Get insights into the airlines that provide service to Boulder. 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 Boulder. Reviews last updated June 23, 2025.
To help decide which airline to fly from Seattle to Boulder, see what other customers have to say about Alaska Airlines, Southwest and Delta. 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

Food

7.1

Entertainment

7.1

Overall

8.0

Crew

8.5

Boarding

8.1

Comfort

7.8

Reviews

1 / 20
8.0
Excellent

Anonymous,Aug 2024

SEA - LAS

Seats were not that comfy especially for someone with big hips 😥
Alaska Airlines
8.0
Very good
10,000 reviews
Alaska Airlines
8.0
Very good
10,000 reviews

Food

7.1

Entertainment

7.1

Overall

8.0

Crew

8.5

Boarding

8.1

Comfort

7.8

Reviews

1 / 20
8.0
Excellent

Anonymous,Aug 2024

SEA - LAS

Seats were not that comfy especially for someone with big hips 😥
Southwest
8.0
Very good
4,278 reviews
Alaska Airlines
8.0
Very good
10,000 reviews

Food

7.1

Entertainment

7.1

Overall

8.0

Crew

8.5

Boarding

8.1

Comfort

7.8

Reviews

1 / 20
8.0
Excellent

Anonymous,Aug 2024

SEA - LAS

Seats were not that comfy especially for someone with big hips 😥
Delta
8.0
Very good
7,966 reviews
Alaska Airlines
8.0
Very good
10,000 reviews

Food

7.1

Entertainment

7.1

Overall

8.0

Crew

8.5

Boarding

8.1

Comfort

7.8

Reviews

1 / 20
8.0
Excellent

Anonymous,Aug 2024

SEA - LAS

Seats were not that comfy especially for someone with big hips 😥
Hawaiian Airlines
7.8
Good
2,520 reviews
Alaska Airlines
8.0
Very good
10,000 reviews

Food

7.1

Entertainment

7.1

Overall

8.0

Crew

8.5

Boarding

8.1

Comfort

7.8

Reviews

1 / 20
8.0
Excellent

Anonymous,Aug 2024

SEA - LAS

Seats were not that comfy especially for someone with big hips 😥
United Airlines
7.4
Good
8,831 reviews
Alaska Airlines
8.0
Very good
10,000 reviews

Food

7.1

Entertainment

7.1

Overall

8.0

Crew

8.5

Boarding

8.1

Comfort

7.8

Reviews

1 / 20
8.0
Excellent

Anonymous,Aug 2024

SEA - LAS

Seats were not that comfy especially for someone with big hips 😥

Related info for your journey

Find useful and relevant information for your journey from Seattle to Boulder. 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 from for flights from Seattle to Boulder?

    Seattle/Tacoma Intl (SEA) is the airport you will fly out of if you book a flight from Seattle to Boulder. You should not have trouble finding flights to Boulder from Seattle/Tacoma Intl; the airport handles an average of 45 outbound flights to Boulder per day. You should also have plenty of airline options to choose from since 7 airlines have flights from the Seattle airport to Boulder. It is only a 11.4 mi journey to Seattle/Tacoma Intl (SEA) from Seattle’s city center.

  • How popular is this Seattle to Boulder flight route?

    Flights from Seattle/Tacoma Intl to Boulder have been viewed 293 times in the past calendar month.

  • What are the cheapest airlines to fly from Seattle to Boulder one-way?

    To fly one-way, consider booking your trip with Delta, which is currently one of the cheapest options available, starting at $79. Frontier flights start at $83 while deals on United Airlines start at $87 one-way.

  • What are the most reliable airlines from Seattle to Boulder?

    Before booking your flight to Boulder from Seattle, check out the most reliable airlines to get you to your destination on time: China Airlines (100%), Aeromexico (100%), LATAM Airlines( 100%).

  • What are the cheapest flights from Seattle to Boulder?

    Looking for the cheapest flight from Seattle to Boulder? While on average our users pay $714, our data indicates the cheapest price to be $80. The most popular route (Seattle/Tacoma Intl - Denver Intl), is priced around $134.

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

    Yes. In addition to deals on Seattle to Boulder flights, Cheapflights offers vacation packages that include both flights and hotel.

  • How can I find direct flights from Seattle to Boulder?

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

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

    Yes. Cheapflights offers flight deals from Seattle to Boulder 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 Seattle to Boulder?

    Currently, October is the cheapest month in which you can book a flight from Seattle to Boulder (average of $197). Flying from Seattle to Boulder in March is currently the most expensive (average of $278). 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

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Top 7 airlines flying from Seattle to Boulder

Discover the top 7 airlines that operate flights from Seattle to Boulder. Compare their services, reliability, and customer satisfaction ratings to choose the airline that best suits your travel preferences and needs. Over the last 7 days, Cheapflights users made 2,558,603 searches. Data last updated June 23, 2025.
AirlineCheapestAverageFlexibilityOn-time
FrontierCheapest$57Average$150FlexibilityNo cancel feeOn-time62%
Hawaiian AirlinesCheapest$98Average$237FlexibilityNo cancel feeOn-time85%
DeltaCheapest$108Average$271FlexibilityNo cancel feeOn-timeN/A
SouthwestCheapest$121Average$315FlexibilityNo cancel feeOn-time63%
United AirlinesCheapest$148Average$369FlexibilityNo cancel feeOn-time69%
Alaska AirlinesCheapest$161Average$292FlexibilityNo cancel feeOn-time75%
American AirlinesCheapest$176Average$275FlexibilityNo cancel feeOn-time71%

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