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

Return flights

19 Sep - 22 Sep	Southwest Airlines
15 Sep - 22 Sep	Southwest Airlines
21 Sep - 25 Sep	Southwest Airlines
16 Sep - 17 Sep	Southwest Airlines
16 Sep - 19 Sep	Southwest Airlines
21 Sep - 27 Sep	Delta
06 Sep - 13 Sep	Delta
20 Sep - 27 Sep	Delta
16 Sep - 23 Sep	Delta
29 Sep - 03 Oct	Delta
23 Sep - 07 Oct	Delta
23 Sep - 29 Sep	Southwest Airlines
26 Sep - 10 Oct	United
20 Sep - 04 Oct	United
21 Sep - 05 Oct	United
28 Sep - 12 Oct	United
25 Sep - 09 Oct	United
30 Sep - 14 Oct	United
24 Sep - 08 Oct	United
27 Sep - 11 Oct	United

Also check the deals for one-way flights from Washington to San Juan in September.

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 September from 132€

Return flights