Hawaii basically has just two seasons, winter and summer:
Summer: Known as Kau in Hawaiian, this summer lasts from May to October. The average daytime summer temperature at sea level is 85 degree Fahrenheit. (29.4 degree Celsius)
Winter: The weather is slightly cooler during the winter, though still quite tropical and warm. There is more rain during the winter, but sunny days are also common. Temperatures in Hawaii are usually in the 70′s and 80′s during the daytime, all year around. Winter known as Hoolio lasts from November to April. The average daytime winter temperature is 78 degree Fahrenheit (25.6 degree Celsius). Temperatures at night are approximately 10 degree Fahrenheit.
Rainy Season: The official rainy season is in the winter from November to March. This month is just a general observation, otherwise it rains every day somewhere on every island regardless of the time of year, and it is more like a sprinkle than a downpour. That is why it is so lush and beautiful there.
It is very rare for it to rain continuously for days. Hurricane season is officially from June to November.
Weather wise you can visit anytime as it is pleasant. Avoid June to November if possible. "High" season is considered from mid-December to mid-April. This is when flights and accommodations are usually more expensive. The summer months are also very busy because kids are out of school. The best time to visit Maui price wise is April, May, September, October, and sometimes November.