$105 Cheap Flights from St. Louis (STL) to San Juan (SJU)

View $105 flight on Mon, Oct 20, 2025Opens in a new window

Popular airlines from St. Louis Lambert Intl. Airport (STL) to Luis Munoz Marin Intl. Airport (SJU)

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Cheap Flights from St. Louis to San Juan (STL-SJU)

Prices were available within the past 7 days and start at $105 for one-way flights and $180 for round trip, for the period specified. Prices and availability are subject to change. Additional terms apply.

Frontier Airlines
Mon, Sep 22 - Sun, Sep 28
STL
St. Louis
SJU
San Juan
$180 Roundtrip, found 6 days ago
$180
Roundtrip
found 6 days ago
Select Frontier Airlines flight, departing Mon, Sep 22 from St. Louis to San Juan, returning Sun, Sep 28, priced at $180 found 6 days ago
Frontier Airlines
Mon, Sep 22 - Sat, Sep 27
STL
St. Louis
SJU
San Juan
$186 Roundtrip, found 6 days ago
$186
Roundtrip
found 6 days ago
Select Frontier Airlines flight, departing Mon, Sep 22 from St. Louis to San Juan, returning Sat, Sep 27, priced at $186 found 6 days ago
Frontier Airlines
Tue, Aug 19 - Sat, Aug 30
STL
St. Louis
SJU
San Juan
$198 Roundtrip, found 6 days ago
$198
Roundtrip
found 6 days ago
Select Frontier Airlines flight, departing Tue, Aug 19 from St. Louis to San Juan, returning Sat, Aug 30, priced at $198 found 6 days ago
Frontier Airlines
Sun, Nov 9 - Sun, Nov 16
STL
St. Louis
SJU
San Juan
$199 Roundtrip, found 6 days ago
$199
Roundtrip
found 6 days ago
Select Frontier Airlines flight, departing Sun, Nov 9 from St. Louis to San Juan, returning Sun, Nov 16, priced at $199 found 6 days ago
Frontier Airlines
Tue, Aug 5 - Fri, Aug 15
STL
St. Louis
SJU
San Juan
$206 Roundtrip, found 6 days ago
$206
Roundtrip
found 6 days ago
Select Frontier Airlines flight, departing Tue, Aug 5 from St. Louis to San Juan, returning Fri, Aug 15, priced at $206 found 6 days ago
Frontier Airlines
Tue, Aug 19 - Fri, Sep 5
STL
St. Louis
SJU
San Juan
$208 Roundtrip, found 6 days ago
$208
Roundtrip
found 6 days ago
Select Frontier Airlines flight, departing Tue, Aug 19 from St. Louis to San Juan, returning Fri, Sep 5, priced at $208 found 6 days ago
Spirit Airlines
Fri, Sep 26 - Sat, Oct 4
STL
St. Louis
SJU
San Juan
$209 Roundtrip, found 4 days ago
$209
Roundtrip
found 4 days ago
Select Spirit Airlines flight, departing Fri, Sep 26 from St. Louis to San Juan, returning Sat, Oct 4, priced at $209 found 4 days ago
Delta
Tue, Oct 21 - Wed, Oct 22
STL
St. Louis
SJU
San Juan
$214 Roundtrip, found 10 hours ago
$214
Roundtrip
found 10 hours ago
Select Delta flight, departing Tue, Oct 21 from St. Louis to San Juan, returning Wed, Oct 22, priced at $214 found 10 hours ago
Southwest Airlines
Tue, Oct 21 - Wed, Oct 22
STL
St. Louis
SJU
San Juan
$214 Roundtrip, found 1 day ago
$214
Roundtrip
found 1 day ago
Select Southwest Airlines flight, departing Tue, Oct 21 from St. Louis to San Juan, returning Wed, Oct 22, priced at $214 found 1 day ago
American Airlines
Sat, Nov 15 - Tue, Nov 25
STL
St. Louis
SJU
San Juan
$219 Roundtrip, found 2 hours ago
$219
Roundtrip
found 2 hours ago
Select American Airlines flight, departing Sat, Nov 15 from St. Louis to San Juan, returning Tue, Nov 25, priced at $219 found 2 hours ago

Find the cheapest month to fly from St. Louis (STL) to San Juan (SJU)

January is typically the cheapest month to fly

From $141 - $504 per traveler.

Graph displaying average flight prices per month

Flights from St. Louis (STL) to San Juan (SJU)
Origin airport
Lambert-St. Louis Intl.
Destination airport
Luis Munoz Marin Intl.
Airlines serving
American Airlines, Delta, Frontier Airlines, Southwest Airlines, Spirit Airlines, United
Roundtrip price
$180
Distance
2024 mi
Average flight time
3 hours 25 mins

St. Louis to San Juan Flights

The cheapest times to fly from St. Louis to San Juan

On average, Thursday can be the cheapest time to fly, according to data from the Airlines Reporting Corporation (ARC), one of the world's biggest databases for global airline sales. The data reveals that you could save up to 16% by flying on a Thursday—the cheapest day to travel on average—instead of a Sunday—the most expensive. Some of the most affordable flights from St. Louis to San Juan are during the month of September. You can find some of the cheapest flights from St. Louis to San Juan with Expedia's search tool and vast selection of airlines.

 

The best time to book a flight from St. Louis to San Juan

Sunday is one of the best days to book for cheap flights from St. Louis to San Juan: Tickets reserved on a Sunday cost between 6% and 13% less than those reserved on a Friday, according to ARC data. The data also suggests booking early can also lead to cheaper airfares. You could save 24% by buying your tickets for domestic flights at least a month in advance and 10% by booking international flights 2 months in advance.

 

How to find cheap round-trip tickets from St. Louis to San Juan

Being flexible with your dates and using Expedia's Price Drop Protection and Price Tracking features are some of the best ways of finding a cheap ticket from St. Louis to San Juan in 2025. You can also book with separate airlines for your outbound and return journeys, from $105 one-way. Expedia also offers Price Drop Protection, so if the cost of your airfare goes down after booking, you'll receive a credit for the difference*. This is available for a small fee, and is free to One Key Gold and Platinum tier members.

 

Expedia's Price Tracking feature means you can stay on top of airfares without manually checking every day. It sends you automated price alerts for cheap St. Louis to San Juan flights and uses historical data to indicate when the best time to book is. Download Expedia's free app to activate this handy tool in a few easy taps.

 

You could also save big by booking one of Expedia's vacation packages. Bundling together your St. Louis to San Juan airfare with your accommodations and car rental is often cheaper than booking everything separately. There’s also One Key, Expedia's generous rewards program. Join for free and you could earn One Key cash on most bookings to save on future adventures.

 

*Terms apply.

 

Disclaimer: ARC The statistics are based on average round-trip ticket prices between January and August 2023. The percentages you see are averages.

 

Frequently asked questions

How much does a flight from Lambert-St. Louis Intl. Airport (STL) to Luis Munoz Marin Intl. Airport (SJU) cost?
Cheap return fares from Lambert-St. Louis Intl. Airport (STL) to Luis Munoz Marin Intl. Airport (SJU) start at $561. This information is based on the cheapest price found on Expedia for this return journey departing within the next three months. This airfare is for a Southwest Airlines flight leaving STL on July 12 2025 and touching down at SJU. The price was last updated on June 30 2025 and has not changed since.
What is the cheapest month to fly from STL to SJU?
The cheapest flights from STL to SJU are usually during off-peak season, when demand is lower. To save money, avoid flying during public holidays, school breaks and major local events.
Which airlines fly direct from Lambert-St. Louis Intl. Airport (STL) to Luis Munoz Marin Intl. Airport (SJU)?
Board a nonstop flight with Southwest Airlines and head straight from Lambert-St. Louis Intl. Airport (STL) to Luis Munoz Marin Intl. Airport (SJU).
What is the cheapest airline that flies from STL to SJU?
With fares starting at $323 for a one-way flight from STL to SJU, Southwest Airlines is currently the cheapest airline on this route. This fare is based on the lowest price found on Expedia departing within the next three months. The flight takes off from STL on July 12 2025. Prices were last updated on June 30 2025 and have not changed since.
How many flights per day from Lambert-St. Louis Intl. Airport (STL) to Luis Munoz Marin Intl. Airport (SJU)?
On average, there are 1 nonstop flights taking off from Lambert-St. Louis Intl. Airport (STL) to Luis Munoz Marin Intl. Airport (SJU) every week. If you don't find one that works for your schedule, consider a flight that has a layover. Customize your search results on Expedia to include one or more stops and opt for the best alternative.
What are the most popular departure times for flights from Lambert-St. Louis Intl. Airport (STL) to Luis Munoz Marin Intl. Airport (SJU)?
The 12 PM departures from STL to SJU see the highest demand. Greater demand means you'll likely pay more for these departures. If you're hoping to save money, book during off-peak hours.
What day of the week has the most flights from STL to SJU?
Travel on a Saturday if you're searching for the largest selection of flights from Lambert-St. Louis Intl. Airport (STL) to Luis Munoz Marin Intl. Airport (SJU).
What is the earliest flight from Lambert-St. Louis Intl. Airport (STL) to Luis Munoz Marin Intl. Airport (SJU)?
Hop on the earliest flight at around 12:50PM UTC-6, departing from Lambert-St. Louis Intl. Airport (STL). You'll be in the air for about 4h 15m, coming in to land at Luis Munoz Marin Intl. Airport (SJU) at approximately 7:05PM UTC-4.
How long does it take to fly from Lambert-St. Louis Intl. Airport (STL) to Luis Munoz Marin Intl. Airport (SJU)?
The average flight duration from STL to SJU is 4 hours and 15 minutes, covering a total distance of 2,000 mi.
What airline has the least delays from STL to SJU?
Southwest Airlines has the best track record for on-time direct flights from Lambert-St. Louis Intl. Airport (STL) to Luis Munoz Marin Intl. Airport (SJU), with an on-time score of 100%. Use the Expedia App to view your journey status before you head off and get notified of any changes.
What is the best time to fly from Lambert-St. Louis Intl. Airport (STL) to Luis Munoz Marin Intl. Airport (SJU)?
Choose a flight from Lambert-St. Louis Intl. Airport (STL) to Luis Munoz Marin Intl. Airport (SJU) that takes off before 3 PM to reduce the risk of cancellations. Departures after this hour are on average 22% more likely to be canceled.**Most reliable time of the day and month to travel recommendation is based on January through August 2024 flight status data sourced from OAG's global flight data platform.
What airports do you fly into for San Juan from Lambert-St. Louis Intl. Airport (STL)?
Luis Munoz Marin Intl. Airport (SJU) is the only airport in San Juan with direct flights from Lambert-St. Louis Intl. Airport (STL). Explore the options and discover cheap fares on Expedia.
Is it cheaper to buy a plane ticket from Lambert-St. Louis Intl. Airport (STL) to Luis Munoz Marin Intl. Airport (SJU) last-minute?
Last-minute fares from STL to SJU are typically more expensive. To secure the cheapest rates, start looking for flights well in advance. That said, if you're flexible with your travel dates, you may land a cheap ticket right before your journey.
Can I cancel or change the date of my flight from Lambert-St. Louis Intl. Airport (STL) to Luis Munoz Marin Intl. Airport (SJU)?
In most cases, you can modify or cancel your STL to SJU flight. However, there may be additional charges, especially if you made your booking over 24 hours ago. Double-check your itinerary for the airline's fees and policies on flight changes, or if you need more details, go to our Customer Service portal.

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