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Key Largo

$70+ 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 9/5. Fares are subject to change and may not be available on all flights or dates of travel.
STL — MIA
Jun 17 — Jun 241
Tue 6/17
Tue 6/24
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 June 12, 2025.

Round-trip from

$199
(American Airlines)

One-way from

$70
(Spirit)

Popular in

March

Cheapest in

August

Average price

$429
From Lambert-St Louis to Key Largo
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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).
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Average for round-trip flights in June 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 June 12, 2025.

This Delta deal was found by Cheapflights users on 6/12. 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.
Mon 7/281:29 pmSTL - MIA
1 stop5h 04mDelta
Thu 7/315:30 amMIA - STL
1 stop5h 11mDelta
Deal found 6/12$201
This FlightHub 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 FlightHub is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 8/307:54 pmSTL - MIA
1 stop9h 36mMultiple Airlines
Sun 9/77:58 pmMIA - STL
1 stop12h 51mMultiple Airlines
Deal found 6/9$208
This Frontier 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 Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sun 8/247:54 pmSTL - MIA
1 stop9h 36mFrontier
Sat 8/307:05 amMIA - STL
1 stop7h 28mFrontier
Deal found 6/11$213
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.
Mon 9/15:22 amSTL - MIA
Nonstop2h 48mAmerican Airlines
Sat 9/610:09 pmMIA - STL
Nonstop2h 50mAmerican Airlines
Deal found 6/11$214
This CheapOair 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 CheapOair is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 9/198:44 amSTL - MIA
1 stop9h 09mSpirit Airlines
Sun 9/215:30 pmMIA - STL
2 stops15h 19mSpirit Airlines
Deal found 6/10$218
This Southwest 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 Southwest is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 7/18:05 amSTL - MIA
Nonstop2h 50mSouthwest
Fri 7/45:55 amMIA - STL
Nonstop2h 50mSouthwest
Deal found 6/11$224
This United Airlines 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 United Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 10/86:15 amSTL - MIA
1 stop8h 32mUnited Airlines
Wed 10/156:05 amMIA - STL
2 stops10h 39mUnited Airlines
Deal found 6/10$362

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 June 12, 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

Mon 7/28

1:29 pm-7:33 pm

1 stop5h 04m

Miami

Thu 7/31

5:30 am-9:41 am

1 stop5h 11m

$201

St. LouisMiami

STL - MIA

STLMIA

Lambert-St Louis

Sat 8/30

7:54 pm-6:30 am

1 stop9h 36m

Miami

Sun 9/7

7:58 pm-7:49 am

1 stop12h 51m

$208

St. LouisMiami

STL - MIA

STLMIA

Lambert-St Louis

Sun 8/24

7:54 pm-6:30 am

1 stop9h 36m

Miami

Sat 8/30

7:05 am-1:33 pm

1 stop7h 28m

$213

St. LouisMiami

STL - MIA

STLMIA

Lambert-St Louis

Mon 9/1

5:22 am-9:10 am

Nonstop2h 48m

Miami

Sat 9/6

10:09 pm-11:59 pm

Nonstop2h 50m

$214

St. LouisMiami

STL - MIA

STLMIA

Lambert-St Louis

Sun 8/3

10:47 am-10:11 am

1 stop22h 24m

Miami

Thu 8/7

4:51 pm-9:52 am

1 stop18h 01m

$220

St. LouisMiami

STL - MIA

STLMIA

Lambert-St Louis

Tue 7/1

8:05 am-11:55 am

Nonstop2h 50m

Miami

Fri 7/4

5:55 am-7:45 am

Nonstop2h 50m

$224

St. LouisMiami

STL - MIA

STLMIA

Lambert-St Louis

Mon 9/1

8:20 am-3:46 pm

1 stop6h 26m

Miami

Sat 9/6

7:28 am-3:44 pm

2 stops9h 16m

$337

St. LouisMiami

STL - MIA

STLMIA

Lambert-St Louis

Mon 8/18

8:44 am-6:53 pm

1 stop9h 09m

$79

St. LouisMiami

STL - MIA

STLMIA

Lambert-St Louis

Tue 7/15

5:00 am-8:49 am

Nonstop2h 49m

$91

St. LouisMiami

STL - MIA

STLMIA

Lambert-St Louis

Tue 7/29

8:05 am-11:55 am

Nonstop2h 50m

$100

Flights are sorted by cheapest round-trip flights first.

Deals found on 6/10

Showing 1-10 of 14 results
1
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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 June 9, 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 $228). 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 June 12, 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 June 12, 2025.

The most flights from STL to KE9 are scheduled on a Wednesday (5 on average). You will have fewer flight options on Sunday, which is when the least amount of flights are scheduled (2 on average).

Rainfall in Key Largo by month

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

In terms of precipitation, rainfall in Key Largo ranges from 1.6 - 9.9 inches per month. September is typically the wettest month, when rainfall can reach 9.9 in. January is typically the driest time to visit Key Largo when rainfall is around 1.6 in.

Temperature in Key Largo by month

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

If weather is an important factor for your trip to Key Largo, 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 84.2 F. Travelers looking to avoid the cold should look outside of January, when temperatures are typically at their lowest (around 68.0 F).

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 June 12, 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 compares in terms of entertainment options, comfort, food, crew/service, and boarding process.
Southwest
8.0
Very good
4,287 reviews

Food

7.1

Entertainment

7.6

Boarding

8.2

Overall

8.0

Comfort

8.0

Crew

8.6

Reviews

1 / 20
8.0
Excellent

John,May 2025

PVD - BNA

It’s southwest so no frills but clean, efficient and got me to my location.
Southwest
8.0
Very good
4,287 reviews
Southwest
8.0
Very good
4,287 reviews

Food

7.1

Entertainment

7.6

Boarding

8.2

Overall

8.0

Comfort

8.0

Crew

8.6

Reviews

1 / 20
8.0
Excellent

John,May 2025

PVD - BNA

It’s southwest so no frills but clean, efficient and got me to my location.
Delta
8.0
Very good
7,946 reviews
Southwest
8.0
Very good
4,287 reviews

Food

7.1

Entertainment

7.6

Boarding

8.2

Overall

8.0

Comfort

8.0

Crew

8.6

Reviews

1 / 20
8.0
Excellent

John,May 2025

PVD - BNA

It’s southwest so no frills but clean, efficient and got me to my location.
United Airlines
7.4
Good
8,790 reviews
Southwest
8.0
Very good
4,287 reviews

Food

7.1

Entertainment

7.6

Boarding

8.2

Overall

8.0

Comfort

8.0

Crew

8.6

Reviews

1 / 20
8.0
Excellent

John,May 2025

PVD - BNA

It’s southwest so no frills but clean, efficient and got me to my location.
American Airlines
7.2
Good
10,000 reviews
Southwest
8.0
Very good
4,287 reviews

Food

7.1

Entertainment

7.6

Boarding

8.2

Overall

8.0

Comfort

8.0

Crew

8.6

Reviews

1 / 20
8.0
Excellent

John,May 2025

PVD - BNA

It’s southwest so no frills but clean, efficient and got me to my location.
Spirit Airlines
6.3
Okay
8,052 reviews
Southwest
8.0
Very good
4,287 reviews

Food

7.1

Entertainment

7.6

Boarding

8.2

Overall

8.0

Comfort

8.0

Crew

8.6

Reviews

1 / 20
8.0
Excellent

John,May 2025

PVD - BNA

It’s southwest so no frills but clean, efficient and got me to my location.

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 4 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 36 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 Spirit Airlines. According to our data, you can fly for as low as $70. Users have also found prices from $89 and $101 on Southwest and Delta, 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 (88%), Southwest (87%) and American Airlines (62%).

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

    On average you can expect to pay $404 for a flight from St. Louis to Key Largo. The cheapest flight overall is $140 while the most popular route, (Lambert-St Louis - Miami) is currently priced at $174.

  • 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 $228). 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 June 12, 2025.
AirlineCheapestAverageFlexibilityOn-time
Spirit AirlinesCheapest$64Average$150FlexibilityNo cancel feeOn-time65%
FrontierCheapest$128Average$236FlexibilityNo cancel feeOn-time62%
DeltaCheapest$199Average$418FlexibilityNo cancel feeOn-timeN/A
American AirlinesCheapest$229Average$416FlexibilityNo cancel feeOn-time71%
United AirlinesCheapest$245Average$487FlexibilityNo cancel feeOn-time69%
SouthwestCheapest$294Average$465FlexibilityNo cancel feeOn-time63%

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