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

Return flights

30 Sep - 07 Oct	Iberia
16 Sep - 23 Sep	British Airways
22 Sep - 01 Oct	KLM
15 Sep - 23 Sep	British Airways
26 Sep - 03 Oct	Iberia
25 Sep - 02 Oct	British Airways
30 Sep - 25 Oct	British Airways
29 Sep - 25 Oct	British Airways
17 Sep - 21 Sep	Virgin Atlantic
25 Sep - 06 Oct	United
28 Sep - 06 Oct	Delta
21 Sep - 11 Oct	Iberia
14 Sep - 25 Sep	United
22 Sep - 18 Oct	British Airways
22 Sep - 29 Sep	Delta
10 Sep - 16 Sep	Delta
14 Sep - 21 Sep	British Airways
13 Sep - 20 Sep	American Airlines
12 Sep - 22 Sep	Delta
25 Sep - 29 Sep	Delta

Also check the deals for one-way flights from Washington to Madrid 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 Madrid in September from 373€

Return flights