The research is directed toward improved modeling of urban climates. An existing simulation model will be extended and improved by: (a) considering a wider range of conditions (seasons, meteorological conditions, canyon geometries) in the simulations; (b) incorporating more complex, but realistic, components that will account for buoyancy effects, moist surfaces, and advection; (c) eliminating unrealistic aspects of the current model; and (d) validating the model against observational studies in the literature. The model can then be used to investigate the causal elements of urban microclimates, and it will also serve as a tool to be used by planners concerned with urban design. Results from this type of modeling are likely to become more important in the design of future cities given that urbanization is increasing at an unprecedented rate and there is greater concern with human comfort and safety in urban environments.