Climatic factors affecting Wright Valley, an ice-free valley between the Upper Wright and Wilson Piedmont Glaciers, are examined, based on observations made between November 15, 1962 and January 1, 1963. The summer weather pattern is controlled primarily by solar radiation, the valley’s absorption rate being three times that of the snow-covered ice sheet on the neighboring plateau. Humidity was very low because of radiational heating, adiabatic heating of air flowing down from the plateau, and a lack of water (as ice) for evaporation. The summer climate is characterized by relatively high air temperatures, very low humidity, and net incoming radiation. The weather log of a typical summer day and significance to helicopter operations are included.