The objective of this paper is to assess the influence of future urban The objective of this paper is to assess the influ ence of future urban growth scenarios on future urban climate in Toulouse metropolitan area (France). Specifically, we aim to test the hypothesis that urban growth based on sprawling patterns has a significant influence on the Urban Heat Island (UHI) phenomena than compact patterns. Urban growth simulations, which are based on three contrasting scenarios built by 2100 with respect to different urban patterns, are made using a new spatially explicit urban growth model (SLEUTHR) which is specifically developed for that purpose. Potential UHI maps of 2006 and by 2100 are estimated under the same climate conditions using the SURFEX climate model. The influence of urban form on urban microclimate is assessed by comparing the estimated UHI map of 2006 with the potential UHI maps expected by 2100 with respect to the scenario-based urban expansion maps. Simulations with Meso-NH shows that, for the 2006 experience, the center of Toulouse is warmer than the surrounding rural areas by about 6.4°C at 00 LT and at 06 LT. The results highlight an increase of 1 to 2 degrees in the urban air temperature at the beginning of the night and a lost of cool capacity in the scenarios. Furthermore, the results show that big differences in the scenarios are found when exploring the horizontal distribution of the UHI. The increase in the urbanised surface b y 2100 leads to a general elevation of temperatures of about 1°C at 00LT and at 06 LT.