This study aimed at assessing community vulnerability and adaptation to the impact of climate variability and extremes on wetlands and its implication for livelihoods in Simiyu catchment, Southwest of Lake Victoria, Tanzania. The results of this study provide baseline information on vulnerability assessments and development of adaptation strategies in the country. Moreover this study will likely contribute significantly to similar future studies on other wetlands within Tanzania. Rainfall anomalies were used to characterise wet and dry seasons. Questionnaire surveys and focus group discussions were used to establish the impacts and coping strategies used during extreme events of floods and droughts. The results showed high rainfall fluctuations between seasons and from one year to the other. They further indicated that normally the October –November –December (OND) and March-April-May (MAM ) seasons do not have the same strength and sign of anomalies, that is there are seasonal variation within the same year. Communities living around the Simiyu wetlands are vulnerable to seasonal fluctuations as their socio-economic activities are highly dependent on rainfall since 87% of respondents practice rainfed agriculture. It is concluded that incidences of climate variations are increasing and have implications for livelihoods that depend on wetlands resources. The implication of these seasonal variations is the reduction in agricultural and livestock production. This has recently led to mixed croping along the wetlands and lake shores as a coping strategy. The responses of livestock keepers to seasonal variations in rainfall include holding vast and varied grazing grounds (transhumance) in order to ensure ownership of abundant grazing land.