The study investigated the effects of climate variability on yield of maize, yam, and cassava in South east Nigeria and the role of agricultural extension on climate variability mitigation and adaptation measures Secondary and primary data were used. Secondary data on climate variables and yield were collected for twenty years (1995-2014) from the Nigeria Meteorological Agency Enugu and from National Bureau of Statistics (NBS) respectively. Primary data were collected from the Agricultural Development Programmes (ADPs) of the three selected states of South East Nigeria by use of structured questionnaire.