Allyn-Grapeview is a former census-designated place (CDP) in Mason County, Washington, United States. At the 2010 census, the CDP was separated into Allyn and Grapeview. The combined 2010 population of the two new CDPs was 2,917. The community-based monthly newspaper called the North Bay Review, services the Allyn-Grapeview area. Allyn's main road and thoroughfare is State Route 3 with Grapeview connected to Route 3 via Grapeview Loop Road.
Geography
Allyn-Grapeview is located on the western shore of North Bay region of Puget Sound's Case Inlet.
According to the United States Census Bureau, the CDP has a total area of 13.8 square miles (35.7 km<sup>2</sup>), of which, 8.5 square miles (21.9 km<sup>2</sup>) of it is land and 5.3 square miles (13.8 km<sup>2</sup>) of it (38.62%) is water.
Climate
This region experiences warm (but not hot) and dry summers, with no average monthly temperatures above 71.6 °F. According to the Köppen Climate Classification system, Allyn-Grapeview has a warm-summer Mediterranean climate, abbreviated "Csb" on climate maps.
Demographics
As of the census
The local community based monthly newspaper called the North Bay Review, services Allyn.