Hilo Hawaii is a census-designated place and the largest city in Hawaii County, Hawaii, United States, which includes the island of Hawaii. Hilo Hawaii has a tropical rainforest climate, so it gets a lot of rain throughout the year. Hilo International Airport got an average of 126.72 inches (3,220 mm) of rain each year from 1981 to 2010, with rain falling on 272 days of the year.