Kesennuma (気仙沼市; -shi) is a city located in the extreme northeast of Miyagi Prefecture. It wraps around the western part of Kesennuma Bay, and also includes the island of Ōshima. Its coastline forms the southern boundary of the Rias Coastline National Park, which stretches north all the way to Aomori Prefecture.
The city borders Hirota Bay, Kesennuma Bay, and the Pacific Ocean to the east and Motoyoshi, Miyagi to the south. Iwate Prefecture makes up the remainder of its borders, with Murone Village to the west, and Rikuzen-Takata City to the north.
The highest point in Kesennuma is 711.9 m high, on the border with Motoyoshi, while the lowest point is at sea level.
The city was founded on June 1, 1953.
Kesennuma is situated in a temperate climate zone and has a moderate climate. The city's average temperature is 10.8°C (53.8°F) and its average annual precipitation is 1,370.6 mm. Its all-time record high is 36.0°C on August 15, 1994, and its all-time record low is -12.6°C on February 17, 1980. The city's climate is fairly similar to Sendai, the largest city in Miyagi Prefecture. Since Kesennuma is located north of Sendai, it is naturally slightly cooler. However, Kesennuma is known to be fairly warm for a city located at its latitude, largely because of ocean currents that flow close by.