Haleakalā National Park in August

April through June and September through November offer the sweet spot of clear skies and manageable crowds. Trade winds typically clear the summit of clouds during these months, giving you better odds for sunrise viewing and stargazing. Summer brings the most visitors but also the most reliable weather. Expect crowds at sunrise viewpoints and book reservations well ahead. Winter can be surprisingly cold—snow occasionally dusts the summit, and strong winds make the already-thin air feel even more brutal. For sunrise, arrive 30-45 minutes early to claim a good spot at Haleakalā Visitor Center or the true summit at Pu'u 'Ula'ula. The show starts about 20 minutes before official sunrise when the sky begins its color transformation. Stargazing peaks during new moon phases when light pollution is minimal. The park's astronomy programs run Friday and Saturday nights, weather permitting. Even without organized programs, the summit offers some of the best amateur stargazing in the world.