August is the cheapest month to fly this route, with average fares around $856 round trip.
Average round-trip fares by departure month, based on current availability.
| Month | Avg Price | Lowest | Relative Cost | |
|---|---|---|---|---|
| May 2026 | $984 | $870 | ||
| June 2026 | $1041 | $894 | Peak | |
| July 2026 | $931 | $847 | ||
| August 2026 | $856 | $791 | Best |
Departing on Sunday offers the lowest average fares at $927. Thursday departures are the most expensive at $1050, a difference of $123.
The best time to fly is August. Set up an alert and we'll notify you when prices drop.
Get Started Free →The cheapest month to fly from Washington DC to London is August, with average round-trip fares around $856. The lowest fare found in August is $791.
Sunday departures are the cheapest, averaging $927 round trip. The most expensive day is Thursday at $1050.
Based on current pricing trends, booking for August travel offers the best value. Avoid June if possible, as fares average $1041 compared to $856 in the cheapest month. May is a solid middle-ground option at $984.
Flying in August instead of June can save you approximately $185 per round trip. The cheapest month averages $856 while the most expensive averages $1041.
Airlines, flight times, price calendar, and more for Washington DC to London
View IAD → LHR Details