The mean annual temperature for Unalaska, the most important island of the group, is about 38° F.; being about 30 for January and about 52° for August.
The average annual amount of rainfall is about 80 in., and Unalaska, with about 250 rainy days per year, is said to be the rainiest place within the territory of the United States.
The principal settlements are on the Unalaska Island.
Of these Iliuliuk (also called Unalaska), the oldest, settled in 17601 775, has a custom house, a Russian-Greek Church, and a Methodist Mission and orphanage, and is the headquarters for a considerable fleet of United States revenue cutters which patrol the sealing grounds of the Pribilofs; adjacent is Dutch Harbor (so named, it is said, because a Dutch vessel was the first to enter it), which is an important port for Bering Sea commerce.
The population of Unalaska Island in 1900 was 575 Aleuts and 66 whites.
The clear days of a year at Unalaska can be counted on the fingers; five days in seven it actually rains or snows.