Cruise Lines always have contingency plans in cases where severe weather is or may affect a cruise ship’s planned course. Depending on the size of the storm, changes to itineraries could range from simply changing the order of the ports visited to the cancellation of a port call altogether.
For weather systems or Hurricanes affecting large areas, sometimes the cruise lines will shift entire itineraries. For example, we recently saw many cruise itineraries changed from the Eastern Caribbean to the Western Caribbean. Cruise lines will usually have enough advance warning of these larger storms so that they can make the necessary changes even before you board your cruise.
Other times, a fast moving system or rapid change in weather can affect a current sailing of a ship. When these circumstances arise, if a ship cannot make it to a port on the scheduled itinerary, it may not always be possible to provide a alternative port of call and the ship will remain at sea and head for calmer waters. Depending on the location of where your ship is sailing, finding an alternative port may be easier where many options may available such as in the Bahamas.
Unless the alternative port is being used as merely an operational stop (for provisions or emergency assistance), then guests would be able to disembark the ship. The time spent in port would be determined by the local authorities and would need to allow for enough time to maintain the schedule for the remainder of the voyage.
In ports where tendering is required, the likelihood of bad weather affecting your chances to visit the port are much greater. If there are strong winds and high seas, moving guests ashore with tenders can become very dangerous and the cruise lines will not take the risk.