Hudson Bay thaws each summer, is frozen for 6 or more months of the year. The polar bears of Hudson Bay have always denned on the land south of Churchill, Manitoba, and appear none the worse for it.
The bears hang around Churchill in the fall, entertaining tourists, scaring the locals, and raiding the garbage dump for food while waiting for the Bay to freeze up so they can head out hunting seals. The DrsC have been to Churchill in the summer, too early in the season to see the bears which were inland hibernating.