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

Return flights

01 Sep - 01 Oct	jetBlue
17 Sep - 22 Sep	jetBlue
09 Sep - 13 Sep	jetBlue
08 Sep - 12 Sep	jetBlue
25 Sep - 28 Sep	jetBlue
01 Sep - 12 Sep	jetBlue
18 Sep - 27 Sep	jetBlue
02 Sep - 05 Sep	jetBlue
17 Sep - 21 Sep	jetBlue
20 Sep - 27 Sep	jetBlue
26 Sep - 29 Sep	jetBlue
30 Sep - 14 Oct	United
21 Sep - 05 Oct	United
27 Sep - 11 Oct	United
19 Sep - 03 Oct	United
22 Sep - 06 Oct	United
20 Sep - 04 Oct	United
24 Sep - 08 Oct	United
28 Sep - 12 Oct	United
29 Sep - 13 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 $302

Return flights