Long-term measurements from several lidar measurements (Rayleigh and sodium) located at 44.0 ¿N, 40.6 ¿N, 34.4 ¿N, and 19.5 ¿N have been used to develop a new climatology of the middle atmosphere temperature. For each instrument, the measurements on every individual day of the year over the entire long-term record were averaged to build a composite year of temperature profiles. These profiles were then interpolated to provide temperature values at 1-km altitude intervals so that the climatology comprises daily temperature values at integer altitudes between 15 and 110 km, depending on the instrument. The climatologies for each lidar were then compared to the CIRA-86 model and to each other. Large differences between the lidar temperatures and the CIRA-86 temperatures are identified and explained. When compared to all instruments, CIRA-86 appears systematically much too cold between 90 and 95 km, by 20 K or more, and possibly 6--8 K too warm around 80 km, making its use as a reference atmosphere model questionable at these altitudes. The annual and semiannual components of the seasonal variability and the 2- to 33-day period variability were investigated. An annual cycle with 6--7 K amplitude in the upper stratosphere, increasing to 15--20 K at 80 km, is observed at midlatitudes. This cycle is in phase with the solar flux in the stratosphere and in opposite phase in the mesosphere with a very cold summer mesopause at 85 km, in good agreement with previous climatologies. At lower latitudes, a semiannual oscillation propagates downward from 85 to 30 km and is characterized by a stronger first cycle than the second (4 and 2 K amplitude respectively). The 2- to 33-day variability at midlatitudes shows a maximum during winter around 40 km and in the mesosphere. The first peak is associated with planetary wave activity and stratospheric warmings and the second to the occurrence of mesospheric temperature inversions. Finally, sudden seasonal transitions, highly consistent between all instruments, have been observed. In particular, in the early winter midlatitudes a two-step warming of the winter mesosphere between 65 and 85 km as well as a cooling of the lower mesosphere appear to be real climatological events rather than some short-term geophysical or instrumental random variability. ¿ 1998 American Geophysical Union