July is the cheapest month to fly this route, with average fares around $306 round trip.
Average round-trip fares by departure month, based on current availability.
| Month | Avg Price | Lowest | Relative Cost | |
|---|---|---|---|---|
| May 2026 | $313 | $274 | ||
| June 2026 | $330 | $264 | Peak | |
| July 2026 | $306 | $254 | Best | |
| August 2026 | $327 | $300 |
Departing on Wednesday offers the lowest average fares at $295. Sunday departures are the most expensive at $361, a difference of $66.
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 San Francisco is July, with average round-trip fares around $306. The lowest fare found in July is $254.
Wednesday departures are the cheapest, averaging $295 round trip. The most expensive day is Sunday at $361.
Based on current pricing trends, booking for July travel offers the best value. Avoid June if possible, as fares average $330 compared to $306 in the cheapest month. August is a solid middle-ground option at $327.
Flying in July instead of June can save you approximately $24 per round trip. The cheapest month averages $306 while the most expensive averages $330.
Airlines, flight times, price calendar, and more for Boston to San Francisco
View BOS → SFO Details