If you're a beach lover, keep in mind that big surf can make many North Shore beaches unswimmable during winter months, while the South Shore gets its large swells in summer. If you want to see the humpback whales, February is the best month, though they arrive as early as December and a few may still be around in early April. In the winter, Napali Coast boat tours can be rerouted due to high seas, the Kalalau Trail can become very wet and muddy or, at times, impassable, and sea kayaking is not an option. If you have your heart set on visiting Kauai's famed coast you may want to visit in the drier, warmer months (May-September).