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Key Largo

$79+ Cheap flights from St. Louis (STL) to Key Largo, FL

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 12/9. Fares are subject to change and may not be available on all flights or dates of travel.
STL — MIA
Aug 3 — Aug 101
Sun 8/3
Sun 8/10
1 adult, Economy
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Cheapflights Tip: The best prices from Lambert-St Louis to Key Largo are usually found in August or September, booked 33 days in advance, depart on a Wednesday or Sunday and return on a Friday

Cheap flight deals from St. Louis to Key Largo

Keep the following information in mind while searching for St. Louis to Key Largo flight deals. Data was last updated July 29, 2025.

Round-trip from

$174
(American Airlines)

One-way from

$79
(American Airlines)

Popular in

March

Cheapest in

August

Average price

$388
From Lambert-St Louis to Key Largo
Search Deals
One-way flight from Lambert-St Louis to Key Largo
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Highest demand for flights based on searches. 9% potential increase in price ($40 potential increase over avg. RT price).
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Cheapest flight prices on average. 2% potential price decrease ($12 potential savings vs. average RT price).
Search Deals
Average for round-trip flights in July 2025
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Find flight deals from St. Louis to Key Largo

Cheapest flights from St. Louis to Key Largo
Explore the most affordable flight options available from St. Louis to Key Largo. Find the lowest fares from popular airlines and budget airlines, with prices last updated on July 29, 2025.

This American Airlines deal was found by Cheapflights users on 7/28. 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.
Sat 8/235:26 amSTL - MIA
Nonstop2h 48mAmerican Airlines
Sat 8/3010:09 pmMIA - STL
Nonstop2h 50mAmerican Airlines
Deal found 7/28$174
This FlightHub deal was found by Cheapflights users on 7/29. 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 FlightHub is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sun 8/312:30 pmSTL - MIA
1 stop17h 48mSpirit Airlines
Sat 9/64:53 pmMIA - STL
1 stop18h 57mSpirit Airlines
Deal found 7/29$189
This Southwest deal was found by Cheapflights users on 7/29. 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.
Sat 10/185:55 pmSTL - MIA
Nonstop2h 40mSouthwest
Sat 10/255:45 amMIA - STL
Nonstop2h 50mSouthwest
Deal found 7/29$194
This Delta deal was found by Cheapflights users on 7/29. 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.
Sat 10/185:15 pmSTL - MIA
1 stop6h 14mDelta
Sat 10/256:00 amMIA - STL
1 stop4h 15mDelta
Deal found 7/29$197
This eDestinos deal was found by Cheapflights users on 7/28. 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 eDestinos is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 9/177:55 pmSTL - MIA
1 stop27h 49mFrontier
Mon 9/225:30 amMIA - STL
1 stop10h 34mFrontier
Deal found 7/28$216
This Mytrip deal was found by Cheapflights users on 7/27. 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.
Thu 9/2512:05 pmSTL - MIA
2 stops21h 45mMultiple Airlines
Mon 9/2911:45 amMIA - STL
2 stops7h 51mMultiple Airlines
Deal found 7/27$240

Cheapflights Fare Finder

 
Customize your flight search to find flights from St. Louis to Key Largo 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 July 29, 2025.
Use the filters below to find and compare flights from St. Louis to Key Largo that are best for you.

Fly from

St. Louis

Fly to

Key Largo

Route

Depart

Return

Price

St. LouisMiami

STL - MIA

STLMIA

Lambert-St Louis

Sat 8/23

5:26 am-9:14 am

Nonstop2h 48m

Miami

Sat 8/30

10:09 pm-11:59 pm

Nonstop2h 50m

$174

St. LouisMiami

STL - MIA

STLMIA

Lambert-St Louis

Sun 8/31

2:30 pm-9:18 am

1 stop17h 48m

Miami

Sat 9/6

4:53 pm-10:50 am

1 stop18h 57m

$189

St. LouisMiami

STL - MIA

STLMIA

Lambert-St Louis

Sat 10/18

5:55 pm-9:35 pm

Nonstop2h 40m

Miami

Sat 10/25

5:45 am-7:35 am

Nonstop2h 50m

$194

St. LouisMiami

STL - MIA

STLMIA

Lambert-St Louis

Sat 10/18

5:15 pm-12:29 am

1 stop6h 14m

Miami

Sat 10/25

6:00 am-9:15 am

1 stop4h 15m

$197

St. LouisMiami

STL - MIA

STLMIA

Lambert-St Louis

Wed 9/17

7:55 pm-12:44 am

1 stop27h 49m

Miami

Mon 9/22

5:30 am-3:04 pm

1 stop10h 34m

$216

St. LouisMiami

STL - MIA

STLMIA

Lambert-St Louis

Thu 9/25

12:05 pm-10:50 am

2 stops21h 45m

Miami

Mon 9/29

11:45 am-6:36 pm

2 stops7h 51m

$240

St. LouisMiami

STL - MIA

STLMIA

Lambert-St Louis

Tue 12/9

4:35 pm-8:20 pm

Nonstop2h 45m

$79

St. LouisMiami

STL - MIA

STLMIA

Lambert-St Louis

Tue 10/14

6:35 pm-10:15 pm

Nonstop2h 40m

$80

St. LouisMiami

STL - MIA

STLMIA

Lambert-St Louis

Thu 10/2

4:00 pm-12:12 am

1 stop7h 12m

$89

St. LouisMiami

STL - MIA

STLMIA

Lambert-St Louis

Wed 10/29

5:15 pm-12:29 am

1 stop6h 14m

$99

Flights are sorted by cheapest round-trip flights first.

Deals found on 7/29

Showing 1-10 of 13 results
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Best time to book a flight from St. Louis to Key Largo

Have a flexible travel schedule? Discover the best time to fly to Key Largo 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 Key Largo

How far ahead should I book a flight from St. Louis to Key Largo?

Use this chart to determine the optimal time to book a round-trip flight from St. Louis to Key Largo. Price data was last updated on July 25, 2025.

To ensure you get the cheapest price possible for a flight from St. Louis to Key Largo, you should look to book at least 33 days in advance of your intended travel date. The price of your flight may increase if you delay and leave booking until a week or so before departure.

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

Currently, September is the cheapest month in which you can book a flight from St. Louis to Key Largo (average of $232). Flying from St. Louis to Key Largo in March is currently the most expensive (average of $289). 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 KE9?

Find hourly flight availability from St. Louis to Key Largo. Discover flight options and departure times throughout the day, allowing you to choose a departure time that suits your schedule. Data last updated July 29, 2025.

Regardless of the time of day you decide to fly, the ticket price will remain around the same. Book flights from St. Louis to Key Largo as you normally would.

What is the cheapest day to fly from St. Louis to Key Largo?

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

Travelers seeking maximum savings on their St. Louis to Key Largo flight should consider departing on Monday evenings when fares are most often at their lowest. Tuesday afternoons flights should be avoided if possible as fares are typically the most expensive at this time.

Weekly flight availability from St. Louis to Key Largo

Explore weekly flight availability from St. Louis to Key Largo. 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 July 29, 2025.

The most flights from STL to KE9 are scheduled on a Saturday (7 on average). You will have fewer flight options on Tuesday, which is when the least amount of flights are scheduled (2 on average).

Reviews of airlines servicing Key Largo

Get insights into the airlines that provide service to Key Largo. 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 Key Largo. Reviews last updated July 29, 2025.
Peruse reviews from past customers who have flown with Southwest, Delta, and United Airlines from St. Louis to Key Largo to help guide your decision. You can also see how each airline stacks up in terms of entertainment options, comfort, food, crew/service, and boarding process.
Southwest
8.0
Very good
4,238 reviews

Boarding

8.1

Overall

8.0

Entertainment

7.5

Comfort

8.0

Crew

8.6

Food

7.0

Reviews

1 / 20
8.0
Excellent

Gina,Jul 2025

LAS - DEN

We experienced bad weather, which turned our 1.5 hour flight from Las Vegas to Denver, into 3.5. The pilot and crew kept us updated and explained that we had to circle and or possibly redirect to another airport. After circling for sometime, we were able to land smoothly in Denver. Thank you to all the flight crew, tower control, and all who got us to our destination safely.
Southwest
8.0
Very good
4,238 reviews
Southwest
8.0
Very good
4,238 reviews

Boarding

8.1

Overall

8.0

Entertainment

7.5

Comfort

8.0

Crew

8.6

Food

7.0

Reviews

1 / 20
8.0
Excellent

Gina,Jul 2025

LAS - DEN

We experienced bad weather, which turned our 1.5 hour flight from Las Vegas to Denver, into 3.5. The pilot and crew kept us updated and explained that we had to circle and or possibly redirect to another airport. After circling for sometime, we were able to land smoothly in Denver. Thank you to all the flight crew, tower control, and all who got us to our destination safely.
Delta
8.0
Very good
7,977 reviews
Southwest
8.0
Very good
4,238 reviews

Boarding

8.1

Overall

8.0

Entertainment

7.5

Comfort

8.0

Crew

8.6

Food

7.0

Reviews

1 / 20
8.0
Excellent

Gina,Jul 2025

LAS - DEN

We experienced bad weather, which turned our 1.5 hour flight from Las Vegas to Denver, into 3.5. The pilot and crew kept us updated and explained that we had to circle and or possibly redirect to another airport. After circling for sometime, we were able to land smoothly in Denver. Thank you to all the flight crew, tower control, and all who got us to our destination safely.
United Airlines
7.4
Good
8,899 reviews
Southwest
8.0
Very good
4,238 reviews

Boarding

8.1

Overall

8.0

Entertainment

7.5

Comfort

8.0

Crew

8.6

Food

7.0

Reviews

1 / 20
8.0
Excellent

Gina,Jul 2025

LAS - DEN

We experienced bad weather, which turned our 1.5 hour flight from Las Vegas to Denver, into 3.5. The pilot and crew kept us updated and explained that we had to circle and or possibly redirect to another airport. After circling for sometime, we were able to land smoothly in Denver. Thank you to all the flight crew, tower control, and all who got us to our destination safely.
American Airlines
7.2
Good
10,000 reviews
Southwest
8.0
Very good
4,238 reviews

Boarding

8.1

Overall

8.0

Entertainment

7.5

Comfort

8.0

Crew

8.6

Food

7.0

Reviews

1 / 20
8.0
Excellent

Gina,Jul 2025

LAS - DEN

We experienced bad weather, which turned our 1.5 hour flight from Las Vegas to Denver, into 3.5. The pilot and crew kept us updated and explained that we had to circle and or possibly redirect to another airport. After circling for sometime, we were able to land smoothly in Denver. Thank you to all the flight crew, tower control, and all who got us to our destination safely.
Spirit Airlines
6.3
Okay
8,040 reviews
Southwest
8.0
Very good
4,238 reviews

Boarding

8.1

Overall

8.0

Entertainment

7.5

Comfort

8.0

Crew

8.6

Food

7.0

Reviews

1 / 20
8.0
Excellent

Gina,Jul 2025

LAS - DEN

We experienced bad weather, which turned our 1.5 hour flight from Las Vegas to Denver, into 3.5. The pilot and crew kept us updated and explained that we had to circle and or possibly redirect to another airport. After circling for sometime, we were able to land smoothly in Denver. Thank you to all the flight crew, tower control, and all who got us to our destination safely.

Related info for your journey

Find useful and relevant information for your journey from St. Louis to Key Largo. 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 St. Louis to Key Largo?

    For a flight from St. Louis to Key Largo, you will be flying from Lambert-St Louis. Lambert-St Louis (STL) is just 12.7 mi from the center of the city. Lambert-St Louis is the only St. Louis airport and it handles 3 outbound flights to Key Largo per day. 6 airlines have flights to Key Largo from Lambert-St Louis on a regular basis.

  • How popular is this St. Louis to Key Largo flight route?

    The Lambert-St Louis to Key Largo flight path was viewed by 49 users in the past month. Keep an eye out for changes in search interest prior to high and low season.

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

    For one-way options, check prices for American Airlines. According to our data, you can fly for as low as $79. Users have also found prices from $80 and $89 on Southwest and Frontier, respectively.

  • What are the most reliable airlines from St. Louis to Key Largo?

    The top 3 most reliable airlines when flying from St. Louis to Key Largo are Qatar Airways (92%), American Airlines (84%) and Envoy Air (83%).

  • What are the cheapest flights from St. Louis to Key Largo?

    On average you can expect to pay $686 for a flight from St. Louis to Key Largo. The cheapest flight overall is $88 while the most popular route, (Lambert-St Louis - Miami) is currently priced at $159.

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

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

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

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

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

    Yes. Cheapflights offers flight deals from St. Louis to Key Largo 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 Key Largo?

    Currently, September is the cheapest month in which you can book a flight from St. Louis to Key Largo (average of $232). Flying from St. Louis to Key Largo in March is currently the most expensive (average of $289). 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.

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Top 6 airlines flying from St. Louis to Key Largo

Discover the top 6 airlines that operate flights from St. Louis to Key Largo. 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 July 29, 2025.
AirlineCheapestAverageFlexibilityOn-time
Spirit AirlinesCheapest$68Average$162FlexibilityNo cancel feeOn-time65%
FrontierCheapest$130Average$246FlexibilityNo cancel feeOn-time62%
DeltaCheapest$199Average$418FlexibilityNo cancel feeOn-timeN/A
American AirlinesCheapest$229Average$419FlexibilityNo cancel feeOn-time71%
United AirlinesCheapest$245Average$486FlexibilityNo cancel feeOn-time69%
SouthwestCheapest$277Average$458FlexibilityNo cancel feeOn-time63%

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