Vehmaa is a municipality of Finland. It is located in the province of Western Finland and is part of the Southwest Finland region. The mu…Vehmaa is a municipality of Finland. It is located in the province of Western Finland and is part of the Southwest Finland region. The municipality has a population of 2,255 and covers an area of 202.09 square kilometres of which 13.32 km² is water. The population density is 11.94 inhabitants per square kilometre.