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

Return flights

11 Sep - 17 Sep	Air Canada
10 Sep - 16 Sep	Aeromexico	direct
03 Sep - 18 Sep	Aeromexico	direct
11 Sep - 15 Sep	Aeromexico	direct
11 Sep - 17 Sep	Aeromexico	direct
14 Sep - 20 Sep	Frontier Airlines
04 Sep - 11 Sep	Frontier Airlines
13 Sep - 21 Sep	Air Canada
11 Sep - 14 Sep	Aeromexico	direct
10 Sep - 15 Sep	Air Canada
22 Sep - 23 Oct	Aeromexico	direct
17 Sep - 01 Oct	United	direct
18 Sep - 02 Oct	United	direct
29 Sep - 13 Oct	United	direct
30 Sep - 14 Oct	United	direct
22 Sep - 06 Oct	United	direct
23 Sep - 07 Oct	United	direct
24 Sep - 08 Oct	United	direct
25 Sep - 09 Oct	United	direct
19 Sep - 03 Oct	United	direct

Also check the deals for one-way flights from Washington to Mexico City 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 Mexico City in September from $400

Return flights