Ōishida has a Humid continental climate (Köppen climate classification Cfa) with large seasonal temperature differences, with warm to hot (and often humid) summers and cold (sometimes severely cold) winters.

[2] Per Japanese census data,[3] the population of Ōishida peaked around the year 1950 has declined in the decades since.

The area of present-day Ōishida was part of ancient Dewa Province and is mentioned in the Engishiki records as the location of a fortified settlement on the highway connecting Akita Castle on the Sea of Japan with Tagajo on the Pacific coast.

After the start of the Meiji period, the area became part of Kitamurayama District, Yamagata Prefecture.

East Japan Railway Company - Yamagata Shinkansen East Japan Railway Company - Ōu Main Line Media related to Ōishida, Yamagata at Wikimedia Commons