The average annual rainfall is 1946 mm with September as the wettest month.

Following the Meiji restoration, the villages of Nakabaru, Kitashigeyasu, Minamishigeyasu, and Mikawa were established with the creation of the modern municipalities system on April 1, 1889.

Miyaki has a mayor-council form of government with a directly elected mayor and a unicameral town council of 16 members.

In terms of national politics, the city is part of the Saga 1st district of the lower house of the Diet of Japan.

The economy of Miyaki is overwhelmingly based on agriculture, mostly rice production.