The weather in Kihei is great most of the time. It gets the littlest rainfall of any place on the island, and the temperatures average between 75-85 degrees year-round. While other areas of Maui tend to have a rainy season from November to March, Kihei gets very little rain, averaging less than twelve inches a year.
The water stays pretty warm all the time, and can sometimes reach 80 degrees in the summer. The weather is always great for surfing, but the waves tend to be bigger in the winter than in the summer, and there are sometimes warnings posted for both surfers and swimmers regarding choppy waters. Still, weather-wise, there’s no time of the year that’s drastically better for visiting than any other.
As far as the tourist season goes, Maui has a pretty consistent ebb and flow as far as how many tourists are on the island at a particular time. The busiest times are when school students have vacation. This allows families to come to the island together. Times like summer vacations, spring break, Thanksgiving and Christmas are the most effected. On the other hand, the times right before or after these dates are always quiet. This makes getting reservations for activities and accommodations easier.