The Diocese generally falls within the Guinea Savannah zone, although some portions of its catchment area (Bawku) are within the Sudan Savannah ecology. The natural vegetation is Savannah woodland consisting of short, deciduous, widely spread fire-resistant grasses and shrubs. Human activities have reduced the vegetation to an open land with some trees of economic value retained.
The annual average rainfall which decreases from south-east to north-west varies from a minimum of 645 mm to a maximum of 1,250 mm with a mean of 1,044mm. Rainfall is limited to one season (Mid April to October) and can be very irregular, with frequent dry spells during June and July which is a critical period for crop growth. The dry season begins from mid-October to the first two weeks of April. This period is characterized by dry, dust-laden North-East Harmattan winds from the Sahara desert.