Blenheim, situated on the Wairau Plain, is mostly flat with surrounding hills, which do not, however, give it as much protection from prevailing winds as might be expected. Open areas in and around Blenheim are hit quite hard by winds blowing in from Cook Strait. Blenheim sits at the confluence of the Taylor and Opawa rivers. Blenheim is in a tectonically active zone and experiences several (usually small) earthquakes each year. The boundary between the Pacific plate (on which Blenheim sits) and the Indo-Australian plate passes just north of Blenheim
