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$436+ 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 9/7. Fares are subject to change and may not be available on all flights or dates of travel.
STL — OPO
jun. 17 — jun. 241
mar. 6/17
mar. 6/24
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 junio 12, 2025.

Round-trip from

$607
(American Airlines)

One-way from

$436
(Kiwi.com)

Popular in

June

Cheapest in

November

Average price

$1,410
From Lambert-St Louis to Porto
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One-way flight from Lambert-St Louis to Porto
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Highest demand for flights based on searches. 24% potential increase in price ($316 potential increase over avg. RT price).
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Cheapest flight prices on average. 3% potential price decrease ($38 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 junio 12, 2025.

This American Airlines deal was found by Cheapflights users on 6/11. 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.
lun. 11/39:20 amSTL - OPO
2 stops16h 20mAmerican Airlines
jue. 11/138:20 amOPO - STL
2 stops17h 40mAmerican Airlines
Deal found 6/11$607
This Orbitz deal was found by Cheapflights users on 6/11. 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.
lun. 11/36:43 pmSTL - OPO
2 stops21h 42mLufthansa
jue. 11/134:15 pmOPO - STL
1 stop27h 40mLufthansa
Deal found 6/11$623
This Iberia deal was found by Cheapflights users on 6/10. 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.
mar. 10/2811:46 amSTL - OPO
2 stops18h 59mIberia
sáb. 11/812:25 pmOPO - STL
2 stops26h 18mIberia
Deal found 6/10$657
This United Airlines deal was found by Cheapflights users on 6/9. 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.
mar. 9/305:24 pmSTL - OPO
1 stop10h 21mUnited Airlines
mié. 10/156:00 amOPO - STL
2 stops15h 44mUnited Airlines
Deal found 6/9$849
This Air Canada deal was found by Cheapflights users on 6/11. 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.
mar. 8/54:00 pmSTL - OPO
2 stops35h 20mAir Canada
mar. 8/1212:50 pmOPO - STL
2 stops29h 37mAir Canada
Deal found 6/11$921
This Gotogate deal was found by Cheapflights users on 6/10. 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 Gotogate is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
mar. 10/284:15 pmSTL - OPO
2 stops38h 00mMultiple Airlines
sáb. 11/16:00 amOPO - STL
2 stops16h 14mMultiple Airlines
Deal found 6/10$1,165

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 junio 12, 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

lun. 11/3

9:20 am-7:40 am

2 stops16h 20m

Porto

jue. 11/13

8:20 am-8:00 pm

2 stops17h 40m

$607

St. LouisPorto

STL - OPO

STLOPO

Lambert-St Louis

lun. 11/3

6:43 pm-10:25 pm

2 stops21h 42m

Porto

jue. 11/13

4:15 pm-1:55 pm

1 stop27h 40m

$623

St. LouisPorto

STL - OPO

STLOPO

Lambert-St Louis

mar. 10/28

11:46 am-11:45 am

2 stops18h 59m

Porto

sáb. 11/8

12:25 pm-8:43 am

2 stops26h 18m

$657

St. LouisPorto

STL - OPO

STLOPO

Lambert-St Louis

mar. 9/30

5:24 pm-9:45 am

1 stop10h 21m

Porto

mié. 10/15

6:00 am-3:44 pm

2 stops15h 44m

$849

St. LouisPorto

STL - OPO

STLOPO

Lambert-St Louis

mar. 8/5

4:00 pm-9:20 am

2 stops35h 20m

Porto

mar. 8/12

12:50 pm-12:27 pm

2 stops29h 37m

$921

St. LouisPorto

STL - OPO

STLOPO

Lambert-St Louis

mar. 10/28

4:15 pm-11:15 am

2 stops38h 00m

Porto

sáb. 11/1

6:00 am-5:14 pm

2 stops16h 14m

$1,165

St. LouisPorto

STL - OPO

STLOPO

Lambert-St Louis

dom. 9/7

8:44 am-7:15 pm

3 stops28h 31m

$436

St. LouisPorto

STL - OPO

STLOPO

Lambert-St Louis

jue. 9/25

1:30 pm-5:05 pm

2 stops21h 35m

$597

St. LouisPorto

STL - OPO

STLOPO

Lambert-St Louis

jue. 9/25

5:24 pm-9:45 am

1 stop10h 21m

$643

St. LouisPorto

STL - OPO

STLOPO

Lambert-St Louis

vie. 10/10

3:30 pm-11:15 am

1 stop13h 45m

$661

Flights are sorted by cheapest round-trip flights first.

Deals found on 6/11

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 $1,047). 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 junio 12, 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 junio 12, 2025.
United Airlines
7.4
Good
8,790 reviews

Entertainment

7.0

Boarding

7.7

Comfort

7.3

Food

6.6

Overall

7.4

Crew

8.1

Reviews

1 / 20
4.0
Okay

Thomas,Mar 2025

SFO - TPE

When I asked for an extra snack, I got an unhappy look from the stewardess. Geez, does one extra snack really affect the bottom line??
United Airlines
7.4
Good
8,790 reviews
United Airlines
7.4
Good
8,790 reviews

Entertainment

7.0

Boarding

7.7

Comfort

7.3

Food

6.6

Overall

7.4

Crew

8.1

Reviews

1 / 20
4.0
Okay

Thomas,Mar 2025

SFO - TPE

When I asked for an extra snack, I got an unhappy look from the stewardess. Geez, does one extra snack really affect the bottom line??
Scandinavian Airlines
7.3
Good
1,387 reviews
United Airlines
7.4
Good
8,790 reviews

Entertainment

7.0

Boarding

7.7

Comfort

7.3

Food

6.6

Overall

7.4

Crew

8.1

Reviews

1 / 20
4.0
Okay

Thomas,Mar 2025

SFO - TPE

When I asked for an extra snack, I got an unhappy look from the stewardess. Geez, does one extra snack really affect the bottom line??
American Airlines
7.2
Good
10,000 reviews
United Airlines
7.4
Good
8,790 reviews

Entertainment

7.0

Boarding

7.7

Comfort

7.3

Food

6.6

Overall

7.4

Crew

8.1

Reviews

1 / 20
4.0
Okay

Thomas,Mar 2025

SFO - TPE

When I asked for an extra snack, I got an unhappy look from the stewardess. Geez, does one extra snack really affect the bottom line??
Air Canada
7.1
Good
9,531 reviews
United Airlines
7.4
Good
8,790 reviews

Entertainment

7.0

Boarding

7.7

Comfort

7.3

Food

6.6

Overall

7.4

Crew

8.1

Reviews

1 / 20
4.0
Okay

Thomas,Mar 2025

SFO - TPE

When I asked for an extra snack, I got an unhappy look from the stewardess. Geez, does one extra snack really affect the bottom line??
Iberia
7.0
Good
2,776 reviews
United Airlines
7.4
Good
8,790 reviews

Entertainment

7.0

Boarding

7.7

Comfort

7.3

Food

6.6

Overall

7.4

Crew

8.1

Reviews

1 / 20
4.0
Okay

Thomas,Mar 2025

SFO - TPE

When I asked for an extra snack, I got an unhappy look from the stewardess. Geez, does one extra snack really affect the bottom line??

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 $607, was found to be the cheapest airline from St. Louis to Porto.Alternate airlines to your destination round-trip include Lufthansa and Iberia. Users have found that American Airlines is 38% cheaper than the other options available to this destination.

  • What are the cheapest airlines to fly from St. Louis to Porto one-way?

    For one-way options, check prices for Scandinavian Airlines. According to our data, you can fly for as low as $597. Users have also found prices from $643 and $661 on United Airlines and Lufthansa, respectively.

  • 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 $1,047). 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 junio 12, 2025.
AirlineCheapestAverageFlexibilityOn-time
LufthansaCheapest$612Average$1,250FlexibilityNo cancel feeOn-time76%
DeltaCheapest$713Average$963FlexibilityNo cancel feeOn-timeN/A
United AirlinesCheapest$751Average$1,091FlexibilityNo cancel feeOn-time69%

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