AirHint found the following cheapest return flights from Boston (BOS) to San Juan (SJU) in October 2025 (see full year).

Return flights

01 Oct - 08 Oct	Spirit Airlines
20 Oct - 22 Oct	Spirit Airlines
04 Oct - 22 Oct	Spirit Airlines
04 Oct - 08 Oct	Spirit Airlines
04 Oct - 17 Oct	Spirit Airlines
05 Oct - 22 Oct	Spirit Airlines
05 Oct - 08 Oct	Spirit Airlines
05 Oct - 17 Oct	Spirit Airlines
01 Oct - 22 Oct	Spirit Airlines
01 Oct - 17 Oct	Spirit Airlines
20 Oct - 08 Nov	Spirit Airlines
21 Oct - 08 Nov	Spirit Airlines
29 Oct - 05 Nov	Delta	direct
24 Oct - 01 Nov	Frontier Airlines
24 Oct - 01 Nov	Delta	direct

Also check the deals for one-way flights from Boston to San Juan in October.

The deals are updated regularly. The prices may go up as tickets are purchased by other travellers. Only the cheapest flights are offered. Select a price to book and secure these cheap prices.

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Cheapest return flights from Boston to San Juan in October from 161€

Return flights