Land Surface Temperature (LST) is one of the main quantities governing the energy exchange between surface and atmosphere. On the extensive Tibetan Plateau (TP), where in-situ observations are usually extremely sparse, accurate knowledge of the land surface energy balance is crucial for understanding and simulating regional processes of meteorology, hydrology and ecology. More specifically, all-weather LST products are required for accurately simulating soil heat transfer, which provides insights into changes in TP permafrost / seasonally frozen ground and regional climate change. However, a major limitation of LST products based on thermal infrared (TIR) remote sensing is that they are limited to clear sky conditions. Recently two all-weather satellite LST products became available: these will be inter-compared, validated and used to simulate and study freeze / thaw on the TP.