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

Return flights

03 Sep - 08 Sep	Aer Lingus	direct
04 Sep - 26 Sep	Aer Lingus	direct
04 Sep - 15 Sep	Aer Lingus	direct
04 Sep - 13 Sep	Aer Lingus	direct
10 Sep - 15 Sep	United
22 Sep - 29 Sep	United
03 Sep - 09 Sep	United
03 Sep - 07 Sep	United
04 Sep - 07 Sep	United
22 Sep - 28 Sep	United
03 Sep - 04 Oct	Ryanair
06 Sep - 31 Oct	Ryanair
28 Sep - 02 Oct	Ryanair

Also check the deals for one-way flights from Shannon to Boston 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 Shannon to Boston in September from $439

Return flights