This study focuses on the application of the EnKF to thermally-driven boundary-layer circulations. The specific case chosen is the land/sea breeze which is the dominant summer-time atmosperic circulation for the Houston/Galveston, Texas area. This phenomenon governs the transport and recirculation of pollutants which have become a major environmental and health concern in recent years in the area of interest. From a data assimilation point of view, modeling of such thermally-driven circulations imposes challenges that have not been previously addressed in the literature. One such very important challenge is the effective use of parameterization schemes, in particular the ones related to boundary layer processes, which are believed to be a major source of error in a land/sea modeling environment. The potential advantages of using the EnKF in such an environment will be demonstrated through the background error covariance structure of a typical sea breeze circulation and preliminary data assimilation results will be presented with the help of a perfect-model analysis and simulated observations.