The Steam Packet is warning two of its Friday sailings are at risk of cancellation.
Gusts of up to 55mph are forecast, leading to moderate to rough seas.
The sailings are the 2:30pm Heysham to Douglas sailing and 7:45pm sailing from the island to Lancashire.
A final decision will be made by 9am on Friday morning.
The company said: “If you have a registered account on our website then you can log on and amend your booking online, alternatively you can contact our reservations team on 01624 661661 or 08722 992 992 make alternative arrangements.”