Cheapest return flights from Washington to Porto in September from $553

Best time to book flights for Washington (IAD) to Porto (OPO) flights at AirHint

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

Return flights

25 Sep - 30 Sep TAP
29 Sep - 06 Oct TAP
18 Sep - 25 Sep TAP
17 Sep - 24 Sep TAP
03 Sep - 09 Sep TAP
16 Sep - 23 Sep TAP
01 Sep - 08 Sep TAP
11 Sep - 18 Sep TAP
21 Sep - 28 Sep United
12 Sep - 19 Sep TAP
13 Sep - 20 Sep TAP

Also check the deals for one-way flights from Washington to Porto in September.

Skyscanner

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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