Chiba Prefecture Ōamishirasato has a humid subtropical climate (Köppen Cfa) characterized by warm summers and cool winters with light to no snowfall.

[2] Per Japanese census data,[3] the population of Ōamishirasato has recently plateaued after a long period of growth.

Ōami Town and Shirasato Village were created during the organization of Sanbu District within Chiba Prefecture with the establishment of the modern municipalities system on April 1, 1889.

[4][5][6] Ōamishirasato has a mayor-council form of government with a directly elected mayor and a unicameral city council of 18 members.

In terms of national politics, the city is part of Chiba 11th district of the lower house of the Diet of Japan.