. Water resources of Cerucuk watershed is highly dependent on rainfall because the geology of Cerucuk watershed is dominated by impervious granitic rock that has a low water storage capacity. Currently water demand in cerucuk watershed increase due to population growth and economic activities. Generally rainfall variability in Indonesia is influenced by Asian and Australia monsoon system, but the seasonal and interseasonal rainfall variability is influenced by ENSO and IOD. This paper aimed to determine the correlation between ENSO and IOD with the rainfall variability of Cerucuk watershed, Belitung island. Data used are monthly rainfall recorded at Buluh Tumbang (1980-2014) and Pilang (1996-2013) stations, monthly and yearly index of Nino 3.4 and Dipole-Mode (1980 - 2014). The statistical and time series analyses were used in this paper. The analysis showed that the monthly and seasonal rainfall of Cerucuk watershed negatively strongly to very strongly correlated with ENSO in Juli - Oktober (dry-monsoon season until transition to wet-monsoon season). The annual rainfall negatively strongly correlated with ENSO and sensitive to the 2, 4, 5, 7 and 8 years of ENSO signal periods. The monthly and seasonal rainfall of Cerucuk watershed negatively strongly to very strongly correlated with IOD in August - November (dry-monsoon season until transition to wet-monsoon season). The annual rainfall negatively strongly correlated with IOD and sensitive to the 2, 4, and 7 years of the IOD signal period. The strong correlation between seasonal rainfall variability with ENSO and IOD occurred at the same time with the strengthening of rainfall correlation with the Indonesia Sea Surface Temperature. ENSO and IOD phenomenon need to be considered in the water resources management of Cerucuk watershed because the phenomenon strongly affects rainfall variability that impacts on water availability. Water resouces management need to be improved as a mitigation and adaptation to the extreme climate events related to global climate phenomenon.