Since havasu is a popular destination, you can go to it anytime except December through March. However, if you want to avoid the crowds and enjoy the serenity of nature in this area, I would suggest going during weekdays or weekends. The trail leading up to Hanauma Bay is only open 8 hours (10am-4pm) on weekdays and 10 hours (8:30-5:30pm) on weekends. So plan accordingly! If you want more information about visiting Hanauma Bay at any time of day or night without getting into that long line for the falls, check out my post here!