My answer is ANY TIME is a great time to go to Maui! Each season highlights a particular character of this enchanting island.
In the summer, the temperatures a generally in the 80s and 90s. During winter, it is (relatively) cooler.
However, two considerations you may want to keep in mind when choosing your travel dates are (1) airline prices and (2) crowds. In general, during peak times, airline prices are high, and in the off-season, you can find some very good deals on flights.
So, between Memorial Day and Labor Day, Thanksgiving weekend, the week between Christmas and New Years, and Easter week, you will find a large number of families and kids. During the fall and winter months, the “snowbirds” come to escape the frost and chill of the Pacific Northwest and Canada.
Maui Moku 