[3] Sennan has a Humid subtropical climate (Köppen Cfa) characterized by warm summers and cool winters with light to no snowfall.

They faced stiff resistance from a local king named Nagamitsu-hiko and during the ensuing battle Itsuse no Mikoto was struck by an arrow.

The village of Tarui was established within Hine District with the creation of the modern municipalities system on April 1, 1889.

Sennan has a mayor-council form of government with a directly elected mayor and a unicameral city council of 15 members.

Sennan collectively with the cities of Kaizuka, Hannan, and the town of Misaki contributes two members to the Osaka Prefectural Assembly.

In terms of national politics, the city is part of Osaka 19th district of the lower house of the Diet of Japan.