AirHint found the following cheapest return flights from Boston (BOS) to Shannon (SNN) in September 2025 (see full year).

Return flights

01 Sep - 10 Sep	Aer Lingus	direct
10 Sep - 22 Sep	United
11 Sep - 20 Sep	United
18 Sep - 22 Sep	United
29 Sep - 03 Oct	Aer Lingus	direct
12 Sep - 02 Oct	Aer Lingus	direct
19 Sep - 29 Sep	Air France
21 Sep - 28 Sep	United

Also check the deals for one-way flights from Boston to Shannon 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 Boston to Shannon in September from 314€

Return flights