All the islands have trade winds, named for the sailing ships brining goods to trade across the ocean. They are what keep our islands comfortable and the heaven they are to visit. Maui's Trade Winds which are from the North East. In the morning, Haleakala tends to block them and it is calm in South Maui (Kihei, Wailea, Makena). This is the best time to snorkel since the waters are clear. As the day progresses, around 11AM to 1 PM the wind often wraps around out of the North and shoots through the "valley" between Haleakala (10,000 ft tall), and the West Maui mountains. I love the way the afternoon breeze cools off the condo but if it really picks up the beaches turn into exfoliating machines. Natures way of keeping you out of the sun too long.
At the south end of the center of the island is Maalaea Harbor where the Coast Guard is and many of the large boats that go to Molokini. This is the windiest harbor in the US and can easily get to 30mph+ in the afternoon. If you rent a condo there, you will be in the windiest spot which is why there are so few available.
Part time Maui resident sharing my Kihei condo with guests when I'm staying in my mainland home.