AirHint found the following cheapest return flights from Washington (DCA) to Porto (OPO) in March 2026 (see full year).

Return flights

10 Mar - 17 Mar	United
11 Mar - 18 Mar	United
09 Mar - 16 Mar	Air France
05 Mar - 18 Mar	United
16 Mar - 23 Mar	KLM
08 Mar - 15 Mar	Delta
07 Mar - 14 Mar	Delta
12 Mar - 19 Mar	United
06 Mar - 18 Mar	Air Canada
31 Mar - 07 Apr	Delta
10 Mar - 04 Apr	Air Canada
13 Mar - 04 Apr	jetBlue
19 Mar - 04 Apr	jetBlue

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

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 Porto in March from $483

Return flights