$45 Cheap Flights to O'Fallon, MO

View $45 flight on Mon, Sep 1, 2025Opens in a new window

Popular airlines to O'Fallon

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How much is the cheapest flight to O'Fallon?

Prices were available within the past 7 days and start at $45 for one-way flights and $83 for round trip, for the period specified. Prices and availability are subject to change. Additional terms apply.

Frontier Airlines
Thu, Sep 4 - Thu, Sep 11
DFW
Dallas
STL
St. Louis
$88 Roundtrip, found 9 hours ago
$88
Roundtrip
found 9 hours ago
Select Frontier Airlines flight, departing Thu, Sep 4 from Dallas to St. Louis, returning Thu, Sep 11, priced at $88 found 9 hours ago
Spirit Airlines
Wed, Jul 30 - Sat, Aug 9
MCO
Orlando
STL
St. Louis
$106 Roundtrip, found 4 hours ago
$106
Roundtrip
found 4 hours ago
Select Spirit Airlines flight, departing Wed, Jul 30 from Orlando to St. Louis, returning Sat, Aug 9, priced at $106 found 4 hours ago
Southwest Airlines
Thu, Aug 7 - Mon, Aug 11
ATL
Atlanta
STL
St. Louis
$137 Roundtrip, just found
$137
Roundtrip
just found
Select Southwest Airlines flight, departing Thu, Aug 7 from Atlanta to St. Louis, returning Mon, Aug 11, priced at $137 just found
United
Tue, Sep 23 - Wed, Sep 24
DEN
Denver
STL
St. Louis
$157 Roundtrip, just found
$157
Roundtrip
just found
Select United flight, departing Tue, Sep 23 from Denver to St. Louis, returning Wed, Sep 24, priced at $157 just found
Hawaiian Airlines
Wed, Dec 10 - Tue, Dec 16
LAX
Los Angeles
STL
St. Louis
$314 Roundtrip, found 1 day ago
$314
Roundtrip
found 1 day ago
Select Hawaiian Airlines flight, departing Wed, Dec 10 from Los Angeles to St. Louis, returning Tue, Dec 16, priced at $314 found 1 day ago

Find the cheapest month to fly from Columbus (CMH) to St. Louis (STL)

August is typically the cheapest month to fly

From $157 - $695 per traveler.

Graph displaying average flight prices per month

Tips to find the cheapest flights to O'Fallon

The cheapest day to fly

Get started finding a cheap flight to O'Fallon on Expedia by either choosing a deal on this page or entering into the search bar your travel dates, origin airport, and whether you want roundtrip or one-way airfare. You can filter for flexibility, number of stops, airline, and departure/arrival times to find the best flight for you.

The cheapest month to fly

September is the cheapest month to fly to O'Fallon. This coincides with the low season when fewer people travel. Whichever month you travel in, though, be sure to book at least a month in advance if you want to score cheap tickets to O'Fallon. ARC's data shows that domestic flights booked 28 days or more before departure are typically 24% cheaper than those booked last minute.

The most affordable time to book a flight

Typically, a Sunday can be the cheapest time to book a flight to O'Fallon, according to ARC’s data. On average, you could save between 6% and 13% by booking on a Sunday instead of a Friday, which is the most expensive day to make a reservation.

The cheapest round-trip tickets to O'Fallon

The lowest price for round-trip flights to O'Fallon in 2025 starts from from $83, while one-way tickets start from from $45. Expedia's effective search tool is one of the best ways to find a budget airfare. Simply enter your dates, and within seconds, it'll show you a vast selection of the cheapest flights to O'Fallon. If you have a preferred departure time or airline, you can use the handy filters to customize your search.

The cheapest airlines flying to O'Fallon

Frontier Airlines, Spirit Airlines, Southwest Airlines, American Airlines, United, Hawaiian Airlines are just some of the airlines that can typically offer cheap tickets to O'Fallon. You can find their most affordable flights by using the “airline” search filter and then sorting prices from low to high. As a trusted partner of the world's leading airlines, Expedia offers you some of the best airfare deals to O'Fallon and countless more destinations worldwide.

The most affordable airports to fly into

To view the cheapest airports to fly into for O'Fallon, simply order your search results from lowest to highest price. Expedia's search tool compares flight prices for all airports close to your destination, so you don't have to manually search them one by one to find the cheapest flight to O'Fallon. If you have a preferred place to fly into, take advantage of the “arrival airport” filter to narrow down your search on Expedia.

Save with a package

With Expedia's amazing package deals, you could save hundreds of dollars by booking your O'Fallon plane tickets together with your accommodations, car rental, or activities. Just select the search wizard's “package” option to view some of the cheapest deals. Look out for the green savings label to see how much you're saving.

Date flexibility for the cheapest flights to O'Fallon

If you can be flexible with your travel dates, it's a good idea to broaden your search by comparing prices on different days. This will open up more options, meaning you could uncover a less expensive flight to O'Fallon.

Stopover savings

The cheapest tickets to O'Fallon are sometimes those with a stopover. Book one of these flights, and you'll change planes at an airport en route to O'Fallon. While the overall travel time might be longer than a non-stop flight, you may decide it's worth it for the money saved.

Get Expedia's Price Drop Protection

Price Drop Protection means that if your flight gets cheaper after booking, you'll be credited the difference*. This gives you peace of mind that you're getting one of the cheapest flights to O'Fallon for your chosen departure. Expedia's Price Drop Protection is available for a small fee but is free to One Key Gold and Platinum tier members.

*Terms apply.

Use our Price Tracking feature

Expedia's Price Tracking feature is another great tool that removes the guesswork from finding cheap flights to O'Fallon. Simply download the free Expedia app to your smart device and activate O'Fallon flight price alerts for your travel dates. There's even a price predictor tool that uses historical data to indicate the best time to book, giving you peace of mind that you'll nab the lowest prices.

Book with Expedia

As well as Price Drop Protection and Price Tracking, Expedia's close partnership with a vast selection of the world's leading airlines means you're sure to find cheap flights to O'Fallon. Plus, the One Key rewards program lets you earn real cash rewards on most bookings that you can use to save money on future trips. Best of all, it's free to join, and members often unlock exclusive discounts, too.

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

What month is the cheapest to fly to O'Fallon?
October is generally the cheapest month for flights to O'Fallon*. Make sure to check for cheap flights during this time as you could snag a good deal. *Cheapest month to fly is based on the month with the cheapest flight found on Expedia.com in the next 330 days.
Which US cities have the cheapest flights to O'Fallon?
Score cheap flights to O'Fallon from Chicago, Dallas and Denver. These cities usually offer the lowest fares to this much-loved destination. But keep in mind that stopovers, holiday periods and demand will also have an impact on rates, so stay flexible and book when you spot a bargain.
Which US cities fly direct to O'Fallon?
Take your pick of 55 US cities providing direct flights to O'Fallon. When reserving on Expedia, click on the "Direct flights only" box to find nonstop routes. Fly to O'Fallon from any of these major cities:

  • Chicago
  • Dallas
  • Denver
  • New York
  • Atlanta

How to find a cheap flight to O'Fallon?
Book your trip early for the best chance of scoring cheap flights to O'Fallon. Also, consider traveling during off-peak months like December and January. If you jet off on a Thursday, you'll save an average of 16% compared to departing on a Sunday.* Save time searching every day and set up a price alert on the Expedia app. We'll send you a notification when fares drop.*Best day of the week to book, depart and ideal booking window recommendations based on average round-trip ticket prices for January through August 2023, sourced from Airline Reporting Corporation's (ARC) global airline sales database. Percentages noted are averages.
How to get a cheap last-minute flight to O'Fallon?
Staying flexible about your plans might help you to find last-minute deals on cheap flights to O'Fallon. To see all the available options, try exploring different ticket types, tweaking your O'Fallon vacation dates, jetting out of an alternative airport or using another carrier.
How far in advance should I book a flight to O'Fallon?
Lock in your flight to O'Fallon two to four months ahead if you're flying in from an international destination. For domestic travel, the general guideline is 28 days in advance. Bigger savings and a greater choice of departure dates, times and seating options are just some of the perks of booking early.**Best day of the week to book, depart and ideal booking window recommendations based on average round-trip ticket prices for January through August 2023, sourced from Airline Reporting Corporation's (ARC) global airline sales database. Percentages noted are averages.
Which day of the week is the cheapest day to buy a plane ticket to O'Fallon?
Sundays are usually the best day to book a cheap flight to O'Fallon, where you can save 8% on average compared to Fridays. If you decide to buy tickets on a Friday, expect to pay more as this is typically the most expensive day.**Best day of the week to book, depart and ideal booking window recommendations based on average round-trip ticket prices for January through August 2023, sourced from Airline Reporting Corporation's (ARC) global airline sales database. Percentages noted are averages.
Which airlines fly to O'Fallon?
There are 10 airlines connecting O'Fallon with 33 airports worldwide. The chief entry point to this city is Lambert-St. Louis Intl. Airport (STL). Book a ticket with any of these leading airlines to O'Fallon:

  • Delta Air Lines
  • American Airlines
  • United Airlines
  • Southern Airways Express

Where do you fly into O'Fallon?
Lambert-St. Louis Intl. Airport (STL) is the main airport for passengers flying to O'Fallon. Or you could touch down at Spirit of St. Louis Airport (SUS). Compare fares between the two airports to find the most cost-effective or convenient way to fly to O'Fallon.
How far is the airport from central O'Fallon?
You'll be roughly 19 mi east of the center of O'Fallon after jetting into Lambert-St. Louis Intl. Airport (STL).
Can I save money by booking an O'Fallon trip package?
You could potentially save hundreds of dollars if you choose an O'Fallon flight and hotel package deal on Expedia. And you'll save yourself hassle by having all your travel arrangements in the same place. Try bundling your hotel and flight with extras such as tours and car rentals for your own personalized O'Fallon vacation.
Can I change or cancel my flight to O'Fallon?
If you booked your flight to O'Fallon in the last 24 hours, you can usually change or cancel it for free. After that, additional charges may apply depending on the airline's terms and conditions. To learn more, head to our Customer Service Portal. Remember that some flights are non-refundable, so you may be offered a credit for a future flight rather than a direct refund. During your search on Expedia, use the "Changes included" or "No cancel fee" filters to compare fares with flexible change policies.
Flights to O'Fallon information
Destination airport
Lambert-St. Louis Intl.
Destination airport IATA code
STL
Destination city name
St. Louis
Roundtrip price
$82

Trending flights to O'Fallon

Prices were available within the past 7 days and start at $45 for one-way flights and $83 for round trip, for the period specified. Prices and availability are subject to change. Additional terms apply.

Frontier Airlines
Thu, Aug 21 - Thu, Aug 21
DFW
Dallas
STL
St. Louis
$83 Roundtrip, found 2 days ago
$83
Roundtrip
found 2 days ago
Select Frontier Airlines flight, departing Thu, Aug 21 from Dallas to St. Louis, returning Thu, Aug 21, priced at $83 found 2 days ago

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*Available to One Key members.