Between June 10 and July 19, 1987, a total of 26 falling spheres have been successfully launched from the Andøya Rocket Range in Norway (69°N, 16°E). From precision radar tracking of the sphere trajectories, 26 temperature profiles were derived for the altitude range 50–90 km. A mean profile, calculated from all data obtained, shows the mesopause to be at an altitude of 88 km and at a temperature of 129±6 K. This mesopause temperature is considerably lower than predicted in some recently developed reference atmospheres. In the middle and upper mesosphere, each of the 26 profiles exhibits a lapse rate close to −6 K/km. These results are compared with parameters obtained previously in winter at the same site.