Aira extends approximately 25 kilometers from north-to-south and approximately 24 kilometers from east-to-west in central Kagoshima Prefecture. Part of the southeast side faces
Kagoshima Bay. In the area facing Kagoshima Bay, four rivers flow from the west: the Oshikawa River, the Beppu River, the Amikake River, and the Hikiyama River.The alluvial plains of these rivers come together to form the Aira Plain, which contains the main urban area. Natural beaches remain on the coast leading to
Kagoshima City on the west side and the coast near the border with
Kirishima City on the east side, but the rest is an artificial coast formed by
reclaimed land. The northern part of Aira City is lined with mountains belonging to the Kitasatsu Volcanic Group, and the border with
Satsumasendai City on the northwest side almost forms the watershed with the
Sendai River basin. A tributary of the Beppu River flows between these mountains, and several villages have developed along it. On the other hand, between Kirishima City and Kirishima City on the northeast side, there is a continuous plateau called Jusanzukahara, and tributaries of the Amikake River and Hikiyama River flow into it from the Kirishima City side. The border with Kagoshima City on the southwest side is the Muregaoka Mountain Range, which has an altitude of around 500 meters, and drops sharply into the plains of Aira City and the coastline. On the north side of the Muregaoka Mountain Range, the Omoi River flows from the Kagoshima City side, and the relatively low-elevation land connects to the center of the former Yoshida Town, which merged with Kagoshima City. A volcano that once existed in the northern part of Kagoshima Bay caused an eruption called the Great Aira Eruption about 25,000 years ago, forming the
Aira Caldera. Aira City is located on the northwest side of this caldera, on the
somma, and there is a stratum called Shirasu, which originated from
pyroclastic flows that flowed out during a large eruption. Other topographical features within the city that originate from volcanic activity include Yonemaru and Sumiyoshi Pond, both of which are said to be
marls. Approximately 65% of Aira's area is forested. The central plains are well-developed
paddy fields, and the area on the plateau bordering Kirishima City on the northeast is an upland farming area.
Neighboring municipalities Kagoshima Prefecture •
Kagoshima •
Kirishima •
Satsuma •
Satsumasendai Climate Aira has a
humid subtropical climate (
Köppen climate classification Cfa). The average annual temperature is about , and the annual rainfall is about . Most of the rainfall is concentrated from June to September. this is the population of Aira in recent years. ==Government==