The performance of a recent version of the general circulation model used at the Goddard Laboratory for Atmospheric Science is evaluated with particular emphasis on its behavior at high latitudes of the Northern and Southern Hemispheres. A January–February climatology for the model was constructed by averaging eight 30-day means, each of which spanned the period from 15 January to 14 February. A mean July climatology was similarly defined on the basis of seven 30-day averages, each spanning the period 1–31 July. Model-generated sea level pressure, 500 mb geopotential, and surface air temperature are compared with observed long-term climatologies. Sensible heat, evaporative, and radiative fluxes at the surface, and radiative fluxes at the top of the atmosphere also are compared with observed data. In the Northern Hemisphere the major features that are satisfactorily simulated include the position and intensity of the Aleutian and Icelandic lows in winter; the central Arctic pressure distribution d... Abstract The performance of a recent version of the general circulation model used at the Goddard Laboratory for Atmospheric Science is evaluated with particular emphasis on its behavior at high latitudes of the Northern and Southern Hemispheres. A January–February climatology for the model was constructed by averaging eight 30-day means, each of which spanned the period from 15 January to 14 February. A mean July climatology was similarly defined on the basis of seven 30-day averages, each spanning the period 1–31 July. Model-generated sea level pressure, 500 mb geopotential, and surface air temperature are compared with observed long-term climatologies. Sensible heat, evaporative, and radiative fluxes at the surface, and radiative fluxes at the top of the atmosphere also are compared with observed data. In the Northern Hemisphere the major features that are satisfactorily simulated include the position and intensity of the Aleutian and Icelandic lows in winter; the central Arctic pressure distribution d...