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$597+ Cheap flights from St. Louis (STL) to Porto (OPO)

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 9/25. Fares are subject to change and may not be available on all flights or dates of travel.
STL — OPO
Jun 28 — Jul 51
Sat 6/28
Sat 7/5
1 adult, Economy
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Cheap flight deals from St. Louis to Porto

Discover tips and strategies to find the most affordable flight options for your journey from St. Louis (STL) to Porto (OPO). 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 June 23, 2025.

Round-trip from

$887
(American Airlines)

Popular in

June

Cheapest in

November

Average price

$1,410
From Lambert-St Louis to Porto
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Highest demand for flights based on searches. 24% potential increase in price ($322 potential increase over avg. RT price).
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Cheapest flight prices on average. 3% potential price decrease ($39 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 St. Louis to Porto

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

This Travelocity 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 Travelocity is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 10/2911:49 amSTL - OPO
2 stops20h 21mLufthansa
Wed 11/56:00 amOPO - STL
1 stop13h 55mLufthansa
Deal found 6/23$601
This Iberia 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 Iberia is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 10/2911:46 amSTL - OPO
2 stops14h 54mIberia
Wed 11/58:20 amOPO - STL
2 stops17h 56mIberia
Deal found 6/23$607
This United 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 United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 10/2811:45 amSTL - OPO
2 stops18h 55mUnited Airlines
Sat 11/86:00 amOPO - STL
2 stops39h 26mUnited Airlines
Deal found 6/22$661
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.
Thu 10/301:30 pmSTL - OPO
2 stops16h 20mDelta
Tue 11/45:00 amOPO - STL
2 stops24h 02mDelta
Deal found 6/23$690
This Air Canada deal was found by Cheapflights users on 6/20. 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 Air Canada is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 9/309:15 amSTL - OPO
2 stops20h 15mAir Canada
Wed 10/156:00 amOPO - STL
2 stops19h 38mAir Canada
Deal found 6/20$767
This American 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 American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 9/199:46 amSTL - OPO
2 stops15h 49mAmerican Airlines
Sat 9/278:15 amOPO - STL
2 stops18h 17mAmerican Airlines
Deal found 6/21$887
This Mytrip 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 Mytrip is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 7/1910:45 amSTL - OPO
2 stops29h 25mMultiple Airlines
Sat 7/266:25 amOPO - STL
3 stops33h 27mMultiple Airlines
Deal found 6/21$1,000
This KLM 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 KLM is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 7/196:04 pmSTL - OPO
2 stops15h 31mKLM
Sat 7/266:05 amOPO - STL
2 stops20h 20mKLM
Deal found 6/21$1,150
This AranGrant 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 AranGrant is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 12/2411:56 amSTL - OPO
2 stops26h 04mBritish Airways
Sun 1/412:25 pmOPO - STL
2 stops39h 37mBritish Airways
Deal found 6/22$2,484

Cheapflights Fare Finder

Customize your flight search to find flights from St. Louis to Porto 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 St. Louis to Porto that are best for you.

Fly from

St. Louis

Fly to

Porto

Route

Depart

Return

Price

St. LouisPorto

STL - OPO

STLOPO

Lambert-St Louis

Wed 10/29

11:49 am-1:10 pm

2 stops20h 21m

Porto

Wed 11/5

6:00 am-1:55 pm

1 stop13h 55m

$601

St. LouisPorto

STL - OPO

STLOPO

Lambert-St Louis

Wed 10/29

11:46 am-7:40 am

2 stops14h 54m

Porto

Wed 11/5

8:20 am-8:16 pm

2 stops17h 56m

$607

St. LouisPorto

STL - OPO

STLOPO

Lambert-St Louis

Tue 10/28

11:45 am-11:40 am

2 stops18h 55m

Porto

Sat 11/8

6:00 am-3:26 pm

2 stops39h 26m

$661

St. LouisPorto

STL - OPO

STLOPO

Lambert-St Louis

Thu 10/30

1:30 pm-10:50 am

2 stops16h 20m

Porto

Tue 11/4

5:00 am-11:02 pm

2 stops24h 02m

$690

St. LouisPorto

STL - OPO

STLOPO

Lambert-St Louis

Tue 9/30

9:15 am-11:30 am

2 stops20h 15m

Porto

Wed 10/15

6:00 am-7:38 pm

2 stops19h 38m

$767

St. LouisPorto

STL - OPO

STLOPO

Lambert-St Louis

Fri 9/19

9:46 am-7:35 am

2 stops15h 49m

Porto

Sat 9/27

8:15 am-8:32 pm

2 stops18h 17m

$887

St. LouisPorto

STL - OPO

STLOPO

Lambert-St Louis

Sat 7/19

10:45 am-10:10 pm

2 stops29h 25m

Porto

Sat 7/26

6:25 am-9:52 am

3 stops33h 27m

$1,000

St. LouisPorto

STL - OPO

STLOPO

Lambert-St Louis

Sat 7/19

6:04 pm-3:35 pm

2 stops15h 31m

Porto

Sat 7/26

6:05 am-8:25 pm

2 stops20h 20m

$1,150

St. LouisPorto

STL - OPO

STLOPO

Lambert-St Louis

Sun 11/2

1:55 pm-11:45 am

2 stops15h 50m

Porto

Thu 11/20

8:20 am-9:41 pm

2 stops19h 21m

$4,002

St. LouisPorto

STL - OPO

STLOPO

Lambert-St Louis

Thu 9/25

1:30 pm-5:05 pm

2 stops21h 35m

$597

Flights are sorted by cheapest round-trip flights first.

Deals found on 6/21

Showing 1-10 of 13 results
1
2

Best time to book a flight from St. Louis to Porto

Have a flexible travel schedule? Discover the best time to fly to Porto from St. Louis 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 St. Louis to Porto

What is the cheapest month to book a flight from St. Louis to Porto?

Currently, January is the cheapest month in which you can book a flight from St. Louis to Porto (average of $523). Flying from St. Louis to Porto in June is currently the most expensive (average of $1,040). 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 STL to OPO?

Find hourly flight availability from St. Louis to Porto. 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.

Unlike in the afternoon, when flights are generally more expensive, you can save up to 36% on flights from St. Louis to Porto by exploring options for tickets at noon.

Rainfall in Porto by month

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

In terms of precipitation, rainfall in Porto ranges from 0.7 - 7.7 inches per month. December is typically the wettest month, when rainfall can reach 7.7 in. July is typically the driest time to visit Porto when rainfall is around 0.7 in.

Temperature in Porto by month

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

If weather is an important factor for your trip to Porto, 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 68.0 F. Travelers looking to avoid the cold should look outside of January, when temperatures are typically at their lowest (around 48.2 F).

Reviews of airlines servicing Porto

Get insights into the airlines that provide service to Porto. 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 Porto. Reviews last updated June 23, 2025.
KLM
7.8
Good
1,365 reviews

Food

7.2

Entertainment

7.1

Overall

7.8

Crew

8.4

Boarding

7.8

Comfort

7.7

Reviews

1 / 20
4.0
Okay

Anonymous,Jun 2025

AMS - BOS

A two and half hour delay caused havoc with all connections. Otherwise on board service was great.
KLM
7.8
Good
1,365 reviews
KLM
7.8
Good
1,365 reviews

Food

7.2

Entertainment

7.1

Overall

7.8

Crew

8.4

Boarding

7.8

Comfort

7.7

Reviews

1 / 20
4.0
Okay

Anonymous,Jun 2025

AMS - BOS

A two and half hour delay caused havoc with all connections. Otherwise on board service was great.
United Airlines
7.4
Good
8,831 reviews
KLM
7.8
Good
1,365 reviews

Food

7.2

Entertainment

7.1

Overall

7.8

Crew

8.4

Boarding

7.8

Comfort

7.7

Reviews

1 / 20
4.0
Okay

Anonymous,Jun 2025

AMS - BOS

A two and half hour delay caused havoc with all connections. Otherwise on board service was great.
American Airlines
7.2
Good
10,000 reviews
KLM
7.8
Good
1,365 reviews

Food

7.2

Entertainment

7.1

Overall

7.8

Crew

8.4

Boarding

7.8

Comfort

7.7

Reviews

1 / 20
4.0
Okay

Anonymous,Jun 2025

AMS - BOS

A two and half hour delay caused havoc with all connections. Otherwise on board service was great.
Air Canada
7.1
Good
9,604 reviews
KLM
7.8
Good
1,365 reviews

Food

7.2

Entertainment

7.1

Overall

7.8

Crew

8.4

Boarding

7.8

Comfort

7.7

Reviews

1 / 20
4.0
Okay

Anonymous,Jun 2025

AMS - BOS

A two and half hour delay caused havoc with all connections. Otherwise on board service was great.
Lufthansa
6.8
Okay
7,182 reviews
KLM
7.8
Good
1,365 reviews

Food

7.2

Entertainment

7.1

Overall

7.8

Crew

8.4

Boarding

7.8

Comfort

7.7

Reviews

1 / 20
4.0
Okay

Anonymous,Jun 2025

AMS - BOS

A two and half hour delay caused havoc with all connections. Otherwise on board service was great.

Related info for your journey

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

  • What are the cheapest airlines flying from St. Louis to Porto round-trip?

    American Airlines, at $887, was found to be the cheapest airline from St. Louis to Porto.Alternate airlines to your destination round-trip include Air Canada and KLM. Users have found that American Airlines is 10% cheaper than the other options available to this destination.

  • Can I find deals for flights from St. Louis to Porto that include hotel bookings?

    Yes. In addition to deals on St. Louis to Porto flights, Cheapflights offers vacation packages that include both flights and hotel.

  • How can I find direct flights from St. Louis to Porto?

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

  • Can I find deals for business class flights from St. Louis to Porto?

    Yes. Cheapflights offers flight deals from St. Louis to Porto 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 St. Louis to Porto?

    Currently, January is the cheapest month in which you can book a flight from St. Louis to Porto (average of $523). Flying from St. Louis to Porto in June is currently the most expensive (average of $1,040). 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

Traveling to a place near St. Louis?

Book flights to St. Louis if you plan to visit one of these locations
Aveiro
Coimbra
Matosinhos
Arcos de Valdevez

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Alternative routes for St. Louis to Porto

See prices for flight routes from nearby airports that may be better suited for you.
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Top 3 airlines flying from St. Louis to Porto

Discover the top 3 airlines that operate flights from St. Louis to Porto. 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
LufthansaCheapest$612Average$1,250FlexibilityNo cancel feeOn-time76%
DeltaCheapest$713Average$963FlexibilityNo cancel feeOn-timeN/A
United AirlinesCheapest$751Average$1,132FlexibilityNo cancel feeOn-time69%

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