Climatic effects represent the physical signals (temperature, wind, humidity, light) which can have a perceptual impact for human-beings. They significantly influence perception and use of urban spaces. Nevertheless, while virtual environments have been proven as good tools to assess urban projects by non-expert people or to study perception in cities, climatic atmospheres are very seldom integrated in the virtual urban model [Drettakis et al. 2007; Tahrani and Moreau 2007]. Indeed, virtual urban environments are represented in ideal situations: the sky is blue, there are a few white clouds, trees are leafy or flowered and the sun is shining. Thus, participants can rarely experiment various seasons, times of day or weathers and and evaluate the urban design under different climatic or lighting situations.