This study investigates how the climate is likely to change in the Mekong Basin by 2030, and quantifies the uncertainty around future climate projections. It provides a preliminary assessment of the potential impact of these changes on water resources and productivity. Our results indicate a likely increase in basin mean temperature of 0.79 oC, with greater increases for the colder catchments in the north of the basin. Annual precipitation is also projected to increase by ~ 0.2 m (13.5%), resulting mainly from an increase in wet season (May to October) precipitation in all catchments. Dry season rainfall is projected to increase in northern catchments, and to decrease in catchments in the south of the basin (including central and southern Laos, eastern Thailand, Cambodia and Vietnam). Our study suggests that the melting of glaciers in the Upper Mekong is likely to increase under 2030 climate projections. However, since the area and volume of glaciers in the basin is small, the impact on flow and water availability in the Lower Mekong basin is likely to be insignificant both during the period of enhanced melting, and after the glaciers have ceased to exist.