Cheap flights from St. Louis to London from £243

In general, October is the cheapest month to fly from St. Louis to London Heathrow Airport. Due to it being the ‘off-season’ during this time, you can expect flight prices to be around £489. The month of April is another great option to travel to London Heathrow Airport, with average flight prices from St. Louis averaging around £544.

On average, the least expensive day to fly to London Heathrow Airport from St. Louis is on a Friday. momondo users have found tickets for Friday departures for as low as £471. However, this price may fluctuate depending on the airline, the season, and holidays. Be sure to avoid booking your departure on a Tuesday as prices are generally higher than usual. According to our data, the average ticket price to London Heathrow Airport on Tuesday is £894.

Fly from Lambert-St Louis to London Heathrow for the best Lambert-St Louis - London Heathrow flight prices

You are more likely to see cheaper flights to London Heathrow Airport from St. Louis when booking weeks ahead of your departure date. In general, you can expect to find flights to London Heathrow Airport for around £704 when searching weeks before you fly. However, flight prices might be lower outside of this timeframe. For example, people recently found flights to London Heathrow Airport from St. Louis for as low as £617 on momondo.

There are 2 cabin classes available to choose from on St. Louis to London Heathrow Airport flights. Cabin price and availability will vary by airline so perform a search above to find the right deals for you.

You could potentially save up to 25% on your flight if you consider stops on a St. Louis to London Heathrow Airport flight.

Historically, on average around 22% of flights between St. Louis and London have experienced a delay on any given week. The average delay length over the past 12 months has been 118 minutes.

Generally, flights departing at night tend to experience fewer delays. Flights departing at night have, in the past, seen delays more frequently in comparison.

Friday is statistically the day of the week that experiences the fewest delays on this flight route. Wednesday has historically seen more delays on average compared to the rest of the week.

According to our data, British Airways have had the fewest delays on this route over the last 12 months, with about 22% of their flights experiencing any sort of delay.

Atlanta (ATL) was the most common stop: 86% of momondo users choosing one-stop flights on this route connected there.

Flights via Dallas (DFW) offer the lowest average return price of £521.

Flights connecting via Atlanta (ATL) have the shortest average one-way travel time: 10h 28m.

Atlanta (ATL) has the shortest average stopover time for this route: 1h 31m.

As of August 2026, there are 2 flights per day flying from St. Louis to London Heathrow Airport. The most common time of day flights depart is 21:00, with 100% of flights taking off in the evening.

The number of flights available between St. Louis and London Heathrow Airport is 15 per week as of August 2026. The most frequent departure day is Tue, with 33% of weekly flights leaving on this day.