The Weymouth Lowlands form a natural region on the south coast of England in the county of Dorset.
According to Natural England, who have designated the Weymouth Lowlands as National Character Area 138, they cover an area of 132.5 square kilometres (51.2 sq mi); a coastal strip between about 1 and 6 kilometres wide, running from the Bride Valley west of Burton Bradstock, to east of Osmington.
The coastline of the Weymouth Lowlands is dominated by Chesil Beach, which hugs the littoral grasslands in the west before separating from the mainland in the east to form The Fleet, a series of brackish lagoons, and then continuing as a narrow causeway linking the mainland with the Isle of Portland.
In the hinterland there are long, rounded, often bare, hogsback ridges interspersed with broad, clay vales.
In the west the landscape is more varied, wooded and undulating than the eastern part of the Lowlands.