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

Return flights

12 Dec - 16 Dec	Aer Lingus	direct
08 Dec - 15 Dec	Aer Lingus	direct
12 Dec - 15 Dec	Aer Lingus	direct
14 Dec - 19 Jan	Aer Lingus	direct
15 Dec - 24 Dec	Aer Lingus
19 Dec - 27 Dec	Aer Lingus	direct
20 Dec - 30 Dec	Aer Lingus
18 Dec - 03 Jan	Icelandair
20 Dec - 04 Jan	Aer Lingus	direct
18 Dec - 03 Jan	Aer Lingus	direct

Also check the deals for one-way flights from Boston to Shannon in December.

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 December from 289€

Return flights