The summer season occurs between May and October, while the winter months are from November to April. Day-time temperatures in the west Maui town of Lahaina during the summer range from an average of 85-88 degrees. while night-time lows average 66-70 degrees. Winter day-time high temperatures there average 81-85 degrees and night-time lows are 63-67 degrees. By comparison, Hana, which is on the east coast, has average summer day-time highs of 81-84 degrees and evening lows of 67-70 degrees. Winter day-time highs there are 78-81 degrees, while night-time lows are 63-68 degrees.

Maui's summer months are mostly sunny to partly cloudy throughout the island, while the winter months of November - March bring an increase of clouds and periodic rain showers. Due to the moist prevailing trade winds, most of Maui's rainfall occurs on its windward north coast, where it supports lush tropical growth and produces hundreds of waterfalls. These rains are highly localized and the majority falls in the remote mountains. A dramatic example of this can be seen by comparing the peak of the West Maui mountains, Pu'u Kukui, which receives over 400 inches of rain per year, verses Lahaina which is only 7 miles away yet receives only 17 inches per year. Because of this highly localized weather, winter rains do not generally disrupt vacationer's plans since there is almost always a sunny spot to be found with a short drive around the coast.

Several times during the year the trade winds will stop completely and the wind will switch around to come out of the south or west, bringing stormy or hot sticky weather for a period of several days. Islanders call this "Kona" weather, because this Polynesian word means leeward or South and it points to the direction from which these weather systems arrive.

The water temperatures at Maui's beaches vary from a high of 80 degrees in the summer, to 77 degrees in the winter. Generally summer waters are very gentle on all beaches, but the surf varies a great deal between winter and summer, and between island coasts. Winter storms far out to sea can bring heavy surf to many north and west facing beaches. Despite this, the popular beaches in the resort areas of Kaanapali, Kapalua, Wailea and Kihei are almost always swimmable. This winter period is the time of year when surfing and sail-boarders abound, which is great fun to watch even if you don't own a board.

Like many other aspects of island weather, the wave conditions are often very localized, so if there is too much surf on your beach, you can usually find calmer water a short drive away on a beach that is sheltered from the prevailing surf. Swimmers should keep in mind that strong currents can make any beach unsafe at any time during the year, but this is particularly true in the winter. When in doubt, simply ask your hotel staff or a local for their recommendations and also watch for warning flags and posted beach conditions.