Hilo features a tropical rainforest climate (Koppen "Af"), with substantial rainfall throughout the course of the year. Hilo's location on the eastern side of the island of Hawaii (windward relative to the trade winds) makes it the wettest city in the United States and one of the wettest cities in the world. An average of around of rain fell at Hilo International Airport annually between 1971–2000, with 275 days of the year receiving some rain. At some other weather stations in Hilo the annual rainfall is above .