July is the cheapest month to fly this route, with average fares around $814 round trip.
Average round-trip fares by departure month, based on current availability.
| Month | Avg Price | Lowest | Relative Cost | |
|---|---|---|---|---|
| May 2026 | $940 | $834 | Peak | |
| June 2026 | $892 | $734 | ||
| July 2026 | $814 | $693 | Best | |
| August 2026 | $848 | $832 |
Departing on Sunday offers the lowest average fares at $802. Friday departures are the most expensive at $951, a difference of $149.
The best time to fly is July. Set up an alert and we'll notify you when prices drop.
Get Started Free →The cheapest month to fly from Boston to Lisbon is July, with average round-trip fares around $814. The lowest fare found in July is $693.
Sunday departures are the cheapest, averaging $802 round trip. The most expensive day is Friday at $951.
Based on current pricing trends, booking for July travel offers the best value. Avoid May if possible, as fares average $940 compared to $814 in the cheapest month. June is a solid middle-ground option at $892.
Flying in July instead of May can save you approximately $126 per round trip. The cheapest month averages $814 while the most expensive averages $940.
Airlines, flight times, price calendar, and more for Boston to Lisbon
View BOS → LIS Details