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