AbstractThis paper analyses wintertime and summertime simulations over Europe using the National Center for Atmospheric Research (NCAR) regional atmospheric model (MM4). The sensitivity of the model to selected physics parametrizations (explicit moisture scheme; slower release of condensation heat; horizontal diffusion on s̀‐surfaces), and lower boundary conditions (sea surface temperature; initial soil moisture; snow cover) is examined. The simulation periods are January 1979 and June 1979; initial and lateral meteorological boundary conditions are provided by analyses of observations. The main focus of the analysis is on prediction by the model of surface air temperature and precipitation, but also sea‐level pressure and upper‐air variables are considered. In general, the model reproduces the main features of the synoptic events which prevailed during the two simulation periods. Mid‐tropospheric and upper‐tropospheric biases in the model are generally small. Surface maximum and minimum air temperature biases do not exceed a few degrees K over various regions of Europe. The largest model bias (2‐3 K) is found for summertime minimum temperature. Wintertime surface temperatures are sensitive to the precipitation parametrizations tested, as these affect cloud formation and, in turn, the surface radiative fluxes. Also, temperature biases in the driving large‐scale fields are partially transmitted to the surface air temperature calculations. Summertime temperatures are sensitive to the soil moisture content. Sea surface temperature variations influence land temperatures more strongly for wintertime than for summertime. Precipitation is sensitive to the parametrizations used. The explicit moisture scheme generally induces underprediction of precipitation. When this is not used, the biases are of the order of −10 to −20% of the observations. Summertime precipitation over the highest Alpine regions is overpredicted, except when diffusion of moisture and temperature along terrain‐following s̀‐surfaces is strongly reduced. Sea surface temperature variations substantially affect precipitation, especially over coastal areas, both in January and June. Summertime precipitation is significantly modified by the initialization of soil water content.