The average annual rainfall ranges from 300mm in the hinterland to 1,300mm at the coastal belt. The coastal belt receives an average annual rainfall of about 900mm to 1,100mm with marked decrease in intensity to the hinterland. Areas with highest rainfall include Mtwapa and to the north of the coastal strip around the Arabuko Sokoke Forest. Evaporation ranges from 1800mm along the coastal strip to 2200mm in the Nyika plateau in the interior. The highest evaporation rate is experienced during the months of January to March in all parts of the county.
The annual temperatures in the county range between 21 oC and 30oC in the coastal belt and between 30oC and 34oC in the hinterland. The county experiences relatively low wind speeds ranging between 4.8 km/hr and 12 Km/hr.College of Biological and Physical Sciences School of Biological Sciences