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

Return flights

25 Oct - 29 Oct	Frontier Airlines
03 Oct - 06 Oct	Frontier Airlines
04 Oct - 06 Oct	Frontier Airlines
12 Oct - 20 Oct	Frontier Airlines
09 Oct - 13 Oct	Frontier Airlines
10 Oct - 13 Oct	Frontier Airlines
16 Oct - 20 Oct	Frontier Airlines
30 Oct - 03 Nov	Frontier Airlines
08 Oct - 08 Oct	United	direct
16 Oct - 20 Oct	United	direct
16 Oct - 21 Oct	United	direct
30 Oct - 03 Nov	United	direct

Also check the deals for one-way flights from Washington 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 Washington to San Juan in October from $210

Return flights