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

Return flights

10 Sep - 17 Sep	Aer Lingus	direct
20 Sep - 24 Sep	Icelandair
02 Sep - 11 Sep	Aer Lingus	direct
01 Sep - 09 Sep	Aer Lingus	direct
01 Sep - 08 Sep	TAP
16 Sep - 23 Sep	Aer Lingus	direct
13 Sep - 25 Sep	Aer Lingus	direct
04 Sep - 11 Sep	Aer Lingus	direct
05 Sep - 12 Sep	Aer Lingus	direct
04 Sep - 10 Sep	Aer Lingus	direct
18 Sep - 02 Oct	TAP
29 Sep - 13 Oct	TAP
27 Sep - 12 Oct	TAP
22 Sep - 02 Oct	TAP
18 Sep - 02 Oct	Aer Lingus	direct
29 Sep - 13 Oct	Aer Lingus	direct
10 Sep - 01 Oct	Air Canada
22 Sep - 02 Oct	Aer Lingus	direct
27 Sep - 12 Oct	United	direct

Also check the deals for one-way flights from Washington to Dublin 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 Dublin in September from 336€

Return flights