August is the cheapest month to fly this route, with average fares around $282 round trip.
Average round-trip fares by departure month, based on current availability.
| Month | Avg Price | Lowest | Relative Cost | |
|---|---|---|---|---|
| May 2026 | $309 | $274 | ||
| June 2026 | $332 | $254 | Peak | |
| July 2026 | $291 | $254 | ||
| August 2026 | $282 | $274 | Best |
Departing on Tuesday offers the lowest average fares at $296. Sunday departures are the most expensive at $321, a difference of $25.
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 San Francisco to Boston is August, with average round-trip fares around $282. The lowest fare found in August is $274.
Tuesday departures are the cheapest, averaging $296 round trip. The most expensive day is Sunday at $321.
Based on current pricing trends, booking for August travel offers the best value. Avoid June if possible, as fares average $332 compared to $282 in the cheapest month. May is a solid middle-ground option at $309.
Flying in August instead of June can save you approximately $50 per round trip. The cheapest month averages $282 while the most expensive averages $332.
Airlines, flight times, price calendar, and more for San Francisco to Boston
View SFO → BOS Details