Kaiyō is located in the southeastern corner of Tokushima Prefecture on the island of Shikoku. It is bordered by the Kii Channel to the southeast and Kochi Prefecture to the southwest. Parts of the town are within the borders of the Chūbu Sankei Prefectural Natural Park.
Kaiyō has a humid subtropical climate (Köppen climate classificationCfa) with hot summers and cool winters. Precipitation is high, but there is a pronounced difference between the wetter summers and drier winters. The average annual temperature in Kaiyō is 16.5 °C (61.7 °F). The average annual rainfall is 3,195.9 mm (125.82 in) with June as the wettest month. The temperatures are highest on average in August, at around 27.4 °C (81.3 °F), and lowest in January, at around 5.9 °C (42.6 °F).[2] The highest temperature ever recorded in Kaiyō was 36.9 °C (98.4 °F) on 23 August 2013; the coldest temperature ever recorded was −7.3 °C (18.9 °F) on 9 January 2021.[3]
Climate data for Kaiyō (2009−2020 normals, extremes 2009−present)
As with all of Tokushima Prefecture, the area of Kaiyō was part of ancient Awa Province. It was noted for ocean-borne shipping, especially of timber, from Tosa Province to the Kinai region . During the Edo period, the area was part of the holdings of Tokushima Domain ruled by the Hachisuka clan from their seat at Tokushima Castle. The area was divided into villages within Kaifu District, Tokushima with the creation of the modern municipalities system on October 1, 1889.
Kaiyō has three public elementary schools and two public middle schools operated by the town government and one public high school operated by the Tokushima Prefectural Department of Education.
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