AirHint found the following cheapest return flights from Washington (IAD) to Cancun (CUN) in September 2025 (see full year).

Return flights

20 Sep - 27 Sep	Aeromexico
27 Sep - 11 Oct	Aeromexico
27 Sep - 01 Oct	Aeromexico
24 Sep - 27 Sep	Aeromexico
06 Sep - 09 Sep	Aeromexico
22 Sep - 03 Oct	Air Canada
22 Sep - 04 Oct	Air Canada
17 Sep - 20 Sep	Air Canada
12 Sep - 19 Sep	Frontier Airlines
20 Sep - 23 Sep	Aeromexico
13 Sep - 15 Sep	Aeromexico
03 Sep - 06 Sep	Air Canada
30 Sep - 10 Oct	Aeromexico
30 Sep - 15 Oct	Aeromexico
27 Sep - 01 Oct	United	direct
08 Sep - 11 Sep	Frontier Airlines
14 Sep - 18 Sep	Frontier Airlines
22 Sep - 06 Oct	Air Canada
22 Sep - 01 Oct	Air Canada
23 Sep - 07 Oct	Aeromexico

Also check the deals for one-way flights from Washington to Cancun 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 Cancun in September from $270

Return flights