Temperature and rainfall patterns in Cambodia are governed by monsoons and characterized by two major wet and dry seasons. The average annual rainfall is 1400 mm in the central low land regions and may reach 4000 mm in certain coastal zones or in highland areas. The annual average temperature is 28 °C, with an average maximum temperature of 38 °C in April and an average minimum temperature of 17 °C in January. This paper presents the climate change scenarios using MAGICC–SCENGEN program, which links emissions scenarios with global and regional climate change and has adopted the regional climate model (PRECIS) in combination with a number of GCM models with resolution of 50×50 km, using observation data and two historical and future climate data sets generated by RCM model downscaling under the two emission scenarios SRES A2 and SRES B2. Projections of maximum and minimum temperatures and rainfall patterns from 2008 to 2099 are described. For future studies, daily data are required perform vulnerability and adaptation assessments.