Size: 923,768 square kilometers.
Boundaries: Southern limits set by Gulf of Guinea (bights of Benin and Biafra); inland frontiers shared with Cameroon (east), Chad (northeast), Niger (north), and Benin (west). No demarcation reached regarding Nigeria-Chad-Niger- Cameroon boundary in Lake Chad, leading to disputes.
Topography: Five major geographic divisions: low coastal zone along Gulf of Guinea; succeeded northward by hills and low plateaus; Niger-Benue river valley; broad stepped plateau stretching to northern border with highest elevations over 1,200 meters; mountainous zone along eastern border, which includes country's highest point (2,042 meters).
Climate: Tropical with variations governed by interaction of moist southwest monsoon and dry northeast winds. Mean maximum temperatures of 30-32ºC (south), 33-35ºC (north). High humidity in south February-November, June-September in north; low humidity during dry season. Annual rainfall decreases northward; about 2,000 millimeters in coastal zone (Niger Delta averages over 3,550 millimeters); 500 to 750 millimeters in north.
Data as of June 1991