Tanzaniäs economy is heavily dependent on rain fed agriculture, thus, climate variability has a strong impact on crop production. This study aims to assess the effects of climate variability on maize yield in Tanzania. Regression, co integration and ARIMA models were applied. The regression results showed that, April monthly rainfall for Arusha was significant (0.0027). There are significant positive long run relationships between maize yield and rainfall for Arusha, Dodoma, Songea, Tabora and Musoma districts. In the case of short run monthly rainfall for Arusha, Dodoma, Songea and Tabora were significantly positive. The fitted ARIMA (p,d,q) model for forecasting monthly rainfall at selected weather stations were computed. The study identified that there is positive relationship between yield and rainfall however; further studies need to be conducted so that we can have broader understanding of the problem for policy action.