Niger has a subtropical climate; it is mainly very hot and dry with much of the land being desert area. Meningitis epidemics typically strike during the dry season from January to June, reaching its peak around April. The wind drives Neisseria Meningitidis which spreads through respiratory droplets. Soon after the rainfall season starts, the epidemic ceases because the respiratory droplets are washed out by the rainfall, and meningitis epidemics start again in the dry season of next year.