Vertical temperature profiles were recorded from June 1999 to October 2002 (at least once a month) at two Mediterranean sites, in the eastern basin (Batroun, Lebanon; 0-100 m) and in the northwestern basin (Marseilles, France; 0-55 m). At the two sites, the thermal seasonal evolution and the thermocline time dynamics are quite identical. But in the Lebanese waters, at comparable water depths, temperatures are currently 4 to 5 .C higher than in the French waters, the thermocline is longer (more than 6 months), permanent and deeper (40-50 m) than in Marseilles (20-30 m). The latter frequently disappears in summer due to northwest winds inducing cold waters. This is principally due to differences in prevailing wind regimes at each site. Such evaluation, coupled with long-term observations of temporal evolution of coastal water at the regional level of the Mediterranean basins, will shed light on temperature regime fluctuations and their consequences in the context of global warming of the Mediterranean.