STL - SJU

$137 Find Cheap Flights from St. Louis to San Juan

This is the cheapest one-way flight price found by a KAYAK user in the last 72 hours by searching for a flight from St. Louis to San Juan departing on 8/11. Fares are subject to change and may not be available on all flights or dates of travel. Click the price to replicate the search for this deal.
1 adult
1 adult, Economy, 0 bags

KAYAK searches hundreds of travel sites at once for deals on flights to San Juan Luis Munoz Marin Intl Airport

 
These are the airlines KAYAK users have selected most often from within our search results in flight searches from St. Louis to San Juan.
These are the airlines KAYAK users have selected most often from within our search results in flight searches from St. Louis to San Juan.
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Everything you should know

Cheapest round-trip
$336
Typical prices: $336-$205
Delta
Wed 9/2Wed 9/9
STL - SJU • 1 stop
Cheapest one-way
$137
Typical prices: $146-$206
Frontier
Tue 8/11
STL - SJU • 2 stops
Advice from real travelers
AI-powered summary based on content written by travel experts. AI can make mistakes.
Avoid peak hours at STL for shorter wait times.
For quick access to San Juan, taxis or Uber are best.
Expert advice
Expert advice
Expert advice
Expert advice
Nonstop flights
1 day a week
Sat
You can fly direct with Southwest. Average duration is 4h 25m
Direct flights
Direct flights
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Direct flights
Direct flights
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Top airlines
Cheapest • from $336 (round-trip)
Best reviews • 8.0 score
Airline reviews
Airline reviews
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Airline reviews
Airline reviews
+1
Top layover airports
Cheapest • Avg $269 (round-trip)
Shortest trip • 7h 19m (one-way)
Insights
Insights
Insights
Insights
Avoid delays
Most punctual • 67% on-time
Best time • Fewest delays
Insights
Insights
Insights
Insights
When to travel
Cheapest • 47% price drop
Most popular
Good to know
Good to know
+1
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Good to know
Good to know
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Start a new search
KAYAK searches 100s of sites at once to find you the best travel deals.
We hope you love your trip to San Juan!
Flight Deals
Booking Insights
Expert advice
Flight Deals

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

 
Here are some of the best deals found on KAYAK recently from the most popular airlines for round-trip flights from St. Louis to San Juan that are departing in the next months. While these flights were available on KAYAK in the last 72 hours, prices and availability are subject to change and deals may expire.
Discover the best prices for you by selecting your travel dates on KAYAK.

Recent round-trip flight deals from St. Louis to San Juan

Wed, Sep 2 - Wed, Sep 9
Delta Logo
6:00 am - 4:35 pm
STL
-
SJU
9h 35m
1 stop
Delta Logo
5:45 pm - 11:37 pm
SJU
-
STL
6h 52m
1 stop
$336Delta
Mon, Jul 6 - Thu, Aug 6
Frontier Logo
4:52 pm - 2:34 pm
STL
-
SJU
44h 42m
2 stops
Frontier Logo
5:15 pm - 8:57 am
SJU
-
STL
16h 42m
1 stop
$343Frontier
Mon, Jul 13 - Fri, Jul 17
Frontier Logo
4:52 pm - 12:41 am
STL
-
SJU
30h 49m
2 stops
Frontier Logo
5:15 pm - 8:57 am
SJU
-
STL
16h 42m
1 stop
$344Frontier
Fri, Aug 7 - Fri, Aug 14
American Airlines Logo
6:03 am - 10:24 pm
STL
-
SJU
15h 21m
1 stop
American Airlines Logo
6:51 am - 11:23 pm
SJU
-
STL
17h 32m
1 stop
$346American Airlines
Wed, Sep 2 - Wed, Sep 9
American Airlines Logo
6:00 am - 6:24 pm
STL
-
SJU
11h 24m
2 stops
American Airlines Logo
6:30 am - 1:22 pm
SJU
-
STL
7h 52m
1 stop
$351American Airlines
Tue, Aug 18 - Sun, Aug 23
Frontier Logo
4:10 pm - 1:54 am
STL
-
SJU
8h 44m
1 stop
Frontier Logo
4:05 pm - 12:14 am
SJU
-
STL
9h 09m
1 stop
$356Frontier
Sat, Sep 5 - Fri, Sep 18
United Airlines Logo
8:00 am - 8:38 pm
STL
-
SJU
11h 38m
2 stops
United Airlines Logo
1:00 am - 12:02 pm
SJU
-
STL
12h 02m
2 stops
$358United Airlines
Sun, Jul 5 - Thu, Aug 6
Frontier Logo
6:33 pm - 2:34 pm
STL
-
SJU
43h 01m
2 stops
Frontier Logo
5:15 pm - 8:57 am
SJU
-
STL
16h 42m
1 stop
$360Frontier
Mon, Jul 13 - Thu, Jul 16
Frontier Logo
4:52 pm - 12:41 am
STL
-
SJU
30h 49m
2 stops
Frontier Logo
5:15 pm - 8:57 am
SJU
-
STL
16h 42m
1 stop
$363Frontier
Fri, Aug 7 - Fri, Aug 14
Frontier Logo
4:52 pm - 6:44 am
STL
-
SJU
36h 52m
2 stops
Frontier Logo
5:15 pm - 8:57 am
SJU
-
STL
16h 42m
1 stop
$366Frontier
Booking Insights

KAYAK's insights & trends for St. Louis to San Juan flights

Get data-powered insights and trends into flights from St. Louis to San Juan to help you find the cheapest flights, the best time to fly and much more.

How much is a round-trip flight from St. Louis to San Juan Luis Munoz Marin Intl Airport?

This analysis is based on the cheapest round-trip price found on KAYAK in the last 12 months by searching for a flight from St. Louis to San Juan Luis Munoz Marin Intl Airport departing in September.

What is the cheapest month to fly from St. Louis to San Juan Luis Munoz Marin Intl Airport?

To calculate monthly average prices, KAYAK takes all prices for each month over the last year for round-trip flights from St. Louis to San Juan Luis Munoz Marin Intl Airport, removes the top 0.1% to account for outliers, and then takes the median of all values for each month.

The cheapest month for flights from St. Louis to San Juan Luis Munoz Marin Intl Airport is September, where tickets cost $224 (return) on average. On the other hand, the most expensive months are December and July, where the average cost of round-trip tickets is $615 and $536 respectively.

How far in advance should I book a flight from St. Louis to San Juan Luis Munoz Marin Intl Airport?

To calculate weekly average prices, KAYAK takes all prices for each week before departure over the last year for round-trip flights from St. Louis to San Juan Luis Munoz Marin Intl Airport, removes the top 0.1% to account for outliers, and then takes the average of all the values for each week.

To get a below average price on the flight from St. Louis to San Juan Luis Munoz Marin Intl Airport, you should book around 1 week before departure. For the absolute cheapest price, our data suggests you should book 14 weeks before departure.

Expert advice

Expert advice for your flight from St. Louis to San Juan

 
AI-powered summary based on content written by travel experts. AI can make mistakes.
KAYAK teamed up with top travel experts to share the best tips for your journey.
Our travel experts
Yulia Denisyuk

Yulia Denisyuk

Expert on STL

Yulia is a freelance journalist who’s dispatched from 90+ countries. Her work focuses on cultures, adventure trips and air travel, appearing in NatGeo, NYT, CNTraveler, and more. For past assignments, she’s stayed with nomads in Mongolia and learned the art of Imigongo in Rwanda. She’s based in Chicago; in winter she often questions that decision.

Gabriel Leigh

Gabriel Leigh

Expert on SJU

Gabriel is a writer and video creator. As senior content producer for Flightradar24 and Monocle’s transport correspondent, he keeps a close eye on aviation in particular. He has also written travel articles for the likes of The New York Times. Born in New York but raised around the world, he now lives in Sweden. He’s been to 75 countries, flying 2.3 million miles on 113 airlines and through 234 airports in the process.

Good to know

Low seasonSeptember
Cheapest flight$137
Best time to beat the crowds with an average 47% drop in price.
Most popular time to fly and prices are also 4% lower on average.
Flight from St. Louis to San Juan

When to book flights from St. Louis to San Juan

Are your dates flexible? Find out the best times to travel from St. Louis to San Juan based on our flight data from the last year. Discover the cheapest month and even day to fly.
Estimated round-trip price
KAYAK looks at all historical flight data for each date to provide a predicted price for one-way trips or round-trips with a duration up to 40 days. While we try to provide actual minimum prices for each date, some prices are predictions and actual prices may differ.

FAQs for booking St. Louis to San Juan flights

  • How many flights are there between St. Louis and San Juan Luis Munoz Marin Intl Airport per day?

    There is a maximum of 1 nonstop flight a day that takes off from St. Louis and lands in San Juan Luis Munoz Marin Intl Airport, with an average flight time of 4h 25m. The most common departure time is 9:00 am and most flights take off in the morning. Each week, there are 1 flights.

  • What is the cheapest flight from St. Louis to San Juan Luis Munoz Marin Intl Airport?

    In the last 3 days, the lowest price for a flight from St. Louis to San Juan Luis Munoz Marin Intl Airport was $137 for a one-way ticket and $336 for a round-trip.

  • Do I need a passport to fly between St. Louis and San Juan?

    Yes, you'll most likely have to show a valid passport before boarding the plane in St. Louis and on arrival in San Juan.

  • Which aircraft models fly most regularly from St. Louis to San Juan?

    The Boeing 737-800 Passenger/BBJ2 (winglets) is the aircraft model that flies most regularly on the St. Louis to San Juan flight route.

  • Which airline alliances offer flights from St. Louis to San Juan?

    Star Alliance, SkyTeam, and oneworld are the airline alliances operating flights between St. Louis and San Juan, with Star Alliance being the most commonly used for this route.

  • On which days can I fly direct from St. Louis to San Juan?

    You can catch a nonstop flight from St. Louis to San Juan on Saturday.

  • Which is the best airline for flights from St. Louis to San Juan, Southwest or Delta?

    The two airlines most popular with KAYAK users for flights from St. Louis to San Juan are Southwest and Delta. With an average price for the route of $512 and an overall rating of 8.0, Southwest is the most popular choice. Delta is also a great choice for the route, with an average price of $389 and an overall rating of 7.9.

  • How does KAYAK find such low prices on flights from St. Louis to San Juan?

    KAYAK is a travel search engine. That means we look across the web to find the best prices we can find for our users. With over 2 billion flight queries processed yearly, we are able to display a variety of prices and options on flights from St. Louis to San Juan.

  • How does KAYAK's flight Price Forecast tool help me choose the right time to buy my flight ticket from St. Louis to San Juan?

    KAYAK’s flight Price Forecast tool uses historical data to determine whether the price for a flight to San Juan from St. Louis is likely to change within 7 days, so travelers know whether to wait or book now.

  • What is the Hacker Fare option on flights from St. Louis to San Juan?

    Hacker Fares allow you to combine one-way tickets in order to save you money over a traditional round-trip ticket. You could then fly to San Juan with an airline and back to St. Louis with another airline. Booking your flights between St. Louis and SJU can sometimes prove cheaper using this method.

  • What is KAYAK's "flexible dates" feature and why should I care when looking for a flight from St. Louis to San Juan?

    Sometimes travel dates aren't set in stone. If your preferred travel dates have some wiggle room, flexible dates will show you all the options when flying to San Juan from St. Louis up to 3 days before/after your preferred dates. You can then pick the flights that suit you best.

Prefer to fly direct from St. Louis to San Juan?

 
Direct data is based off flight results for the next 60 days. Find direct flights from all airlines flying direct from Lambert-St Louis to San Juan Luis Munoz Marin Intl.
Find which airlines fly direct from Lambert-St Louis Airport to San Juan Luis Munoz Marin Intl Airport, which days they fly and book direct flights.

Direct departures

Lambert-St Louis to San Juan Luis Munoz Marin Intl

Saturday

Southwest

Southwest

See more direct flights

Direct returns

San Juan Luis Munoz Marin Intl to Lambert-St Louis

Saturday

Southwest

Southwest

See more direct flights

Reviews of the top 5 airlines serving from St. Louis to San Juan

 
See real verified KAYAK customer reviews for airlines flying from St. Louis to San Juan. Airline scores are aggregated from all reviews left by passengers on KAYAK after flying with an airline. KAYAK doesn’t show reviews that are older than 5 years. Learn how KAYAK collects reviews.
Need help choosing which airline to fly with from St. Louis to San Juan? KAYAK airline reviews give an overall score for each airline based on loads of factors, including comfort, boarding, in-flight entertainment and more, to make your decision easier. See airline scores according to verified KAYAK customer reviews.
8.0
SouthwestOverall score based on 4295 reviews
8.0Comfort
8.6Crew
7.5Entertainment
8.1Boarding
7.0Food
Airline reviews

The checking experience in Orlando was terrible, almost missed the flight. Too many travelers and Southwest completely understaffed.

2.0 MediocreAnonymous, May 2026
MCO - MDW
Read more Southwest reviews

The checking experience in Orlando was terrible, almost missed the flight. Too many travelers and Southwest completely understaffed.

I'm glad it wasn't only 75% full because I could get a good seat

if I was good. Not happy that I have to pay extra money to get the seat I need for lake room, but I guess that’s a sign of the times.

Seats were very comfortable. They tilted back. Drinks and snacks were free and served 3 times. Attendants were awesome.

Plane was clean and comfortable. Flight attendants and gate staff were professional, friendly and efficient. Boarding and deplaning were orderly and efficient. All in all, the typical excellent Southwest experience.

Truly terrible. Will never willingly fly southwest again. Seats are worse than before they switched to assigned seating. One flight attendant was the opposite of helpful (rude, unhelpful, dismissive, and as my stranger seatmate said unprompted: a total prick). This caused me, 15 minutes into the flight, to book an alternate return flight home on a competing airline (first class 1.2k purchase instead of my existing planned flight) just so I would not have to ever be on that aircraft, with that terrible service person, with those horrific seats ever again.

Not having a five hour delay with little notice! The crew was very kind, though, and just as tired as we passengers were. The flight didn't depart until nearly 1 am...and no reason was ever given.

The entire experience from boarding to landing was amazing! The crew were very friendly. Will definitely be back.

no service at all due to turbulence. they should've at least given us snacks, there were only 10 people on the entire flight.

First time I've had to use the disabled accommodations. And I could not have had a better experience with Southwest, i was having trouble getting from one terminal to another due to my heart failure. And the next thing I know a Southwest agent had made sure. I had a wheelchair at all my flights. Can't thank them enough.

Enjoyed it very much. Especially liked the free WiFi that Delta offers.

Smooth flight. Left on time, and got in 15 minutes early. Onboard video was great

For some reason, TSA Atlanta didn’t have my bag on the flight on time and they don’t have to provide Delta a reason for that.

WiFi didn’t work on two of four planes. Flight attendants were not overly friendly or welcoming. Planes were extremely slow to board and deplane.

Delta does a great job with entertainment and free wifi. I can still be in touch with my colleagues while in the air.

Aside from a completely packed plane, I really have no complaints.

Bus to plane was delayed for no apparent reason and our luggage was still on the belt when they shut it off. Took about 20 minutes to turn it back on to get our luggage.

It was a pleasant surprise to have complimentary Wi-Fi on the flight

Much better than Latam, the worse airline company ever. I hope I don't have the need to fly Latam ever in my life again.

Seats in Delta Main are unbelievably close to the seat in front of. Hard to get a backpack under the seat.

No complaints other than luggage carousel was incorrectly guiding passengers to the wrong carousel on the screen.

Did not like that we couldn't complete check in on-line without providing pictures of our passports. Worry about identity theft. We had no delays and boarding was handled In an efficient manner.

We were a little disappointed to not be able to complete check in online without uploading pics of passports. Also we have KTN's and they weren't on our boarding passes when we got to security. Had to trek back to counter to have them fix.

Excellent service in Polaris class IAD to ZRH. Arrived rested and well fed after the overnight flight.

My flight time was changed without any notification to me which ruined my time sensitive plans so I ended up completely changing my travel plans and no reimbursement.

Excellent! I got to Munich and was transferred to my Lufthansa flight quickly, in 15 to 20 minutes, so I did not miss my flight. However, I had checked my overhead bag at the boarding gate in Tampa. That got to Tunis the next day. That is to be expected.

It's a short hop. My carryon was checked at the gate, I didn't have to drag it all over the airport. Excellent wheelchair assist.

WiFi didn’t exist , seats were super cramped, lights stayed on near my seat for a long time while others were dimmed, the food/trash/drink cart hit my shoulder at least a couple of times while moving, food options were down to just one option by the time it got to my row, the utensils were garbage (knife bent at a couple of places by the time I was done eating) the spoon was very flimsy plastic

Friendliest Flight Attendant I’ve seen since I flew on Southwest Airlines. The whole trip was outstanding…and arrived Early!

It was good overall except from Omaha to Denver when flight a was a repeatedly delayed apparently due to some issue at Denver. Communications could have been handled better. I had to board then deboard with luggage and board again

Fine. Nothing to write home about. The plane left on time, and arrived on time.

I was downgraded from first class to coach due to an airplane change. They pulled me out of line and I was the very last person to board the plane stuck in the middle seat with no overhead place to put my carry-.on. Very poor customer service.

Seat comfort was poor (no lumbar or lower back support).

The airplane seats were spacious and comfortable, and the flight attendants were friendly and attentive. The food was delicious like never before. The blankets and toiletries were thoughtfully provided. The captain's navigation was steady and reliable. In short, having flown with Starlux, I won't consider any other airline next time.

STOP MAKING THE SEATING SO CRAMPED. WE NEED A PASSENGER BILL OF RIGHTS!

The passenger in front of of me reclined their seat back all the way the entire flight. Their headrest was in my face the entire flight! I barely had room for the little plastic cup of water to fit on my tray table; can you make the seats and space between the rows any smaller??? You can’t even get up to use the restroom! Worst flight I’ve had in a very long time!

We had several flights and they were all on-time and flawless

My Frequent Flyer nber wasn't put on as I was told it was..... This resulted in a last group boarding and no priority tags on My bags.

Premium Economy Good crew, good service, excellent food. Seat back screen just not bright enough.

Terrible steward... Plane was quite empty... I asked to move "back" in the plane and the steward said no... Unnecessary power trip of mediocre people.

The staff at the check in counter was so rude. Made you feel Incompetent

Frontier scheduled a 40 minute connection in DEN. What they failed to mention was that they “close the doors” 20 mins prior to departure, which means you only have 20 mins. Not enough time. Possibly against DOT regulations. Filing complaint.

Flight was scheduled at 9:40pm. Got delayed to 10 am, the next day. crazy

The bag check, flight check-in, and onboard experience convinced my wife and me that we will actively go out of our way to avoid flying Frontier Airlines in the future. At bag check, we were informed that check-in could only be completed via the Frontier mobile app. Unfortunately, the app was extremely frustrating—sending us through repetitive, confusing loops that repeatedly forced us to decline add-on services with nearly every click. While most airline apps upsell, this one felt intentionally exhausting. As the process dragged on, we became genuinely concerned that my phone battery would die before check-in could be completed. We approached the bag check staff—who were standing together talking—and explained both our frustration and our predicament. They laughed. Later, my wife described the interaction as “gaslighting,” which felt accurate. We were then informed it would cost $25 per person simply to have our boarding passes printed. From that point forward, the tone of the experience was consistently hostile. The bag check employees were condescending and combative, behaving more like bullies than customer service staff. Unfortunately, that same attitude continued onboard. One flight attendant argued with me when I attempted to stow my backpack in the overhead bin. I explained that we had each paid $75 to check our bags specifically so we would not need to use carry-on space and could have adequate legroom. She demanded to see my ticket, pointed out that it said “no carry-on”—which I acknowledged—and I reiterated that this was precisely why we paid to check our bags. Her response was, “I don’t make the rules.” She then walked away, but not before asking if I “truly wanted to fly back to Chicago today?”—an unnecessary and unmistakable threat. It is also worth noting that despite booking our tickets together in the same transaction, we were not seated together. Upon our return to Chicago—where we could once again sit together—we compared onboard experiences. We both remarked on how unhappy the flight attendants appeared and how each of us was separately asked whether we would like to purchase a beverage. We declined. At no point was water mentioned as an option, leaving us with the clear impression that even water came at a cost—or that complimentary water, if available at all, was deliberately left unmentioned. Overall, the experience was shocking and deeply disappointing, but it was also a profound learning experience—one we will not forget and will not repeat. -Steve

Plane was hot and miserable and the crew was rude!

12 hour delay required getting on and off plane 3 times - would have at least liked to have been offered a snack or drink

They didn’t offer a water, even after I asked

They switched our terminal 3 times and we were delayed for four plus hours!!!

It was an early flight and most people napped/slept and the crew let us which was nice.

The crew acted like they had never done this and kept barking passive aggressive orders at people. + the security line + the delay + sitting on the tarmac for 2 hours + none of the apps or signage updating with correct times

Everything you need to know for your flight from St. Louis to San Juan

Information on your arrival and departure airports