The mountainous regions of the north are considerably colder than the south. Winter snows in the Serra da Estrêla (which contains Portugal's highest peak at 1,986 meters) and the Serra do Gerês near the northern Spanish border may block roads for a time. The weather along the northern coasts and in the center of the country is milder; Lisbon has an average high temperature of 14°C in January and 27°C in August. Southern Portugal is warmer. The ocean moderates coastal temperatures, but the interior of the Alentejo can be quite warm, with temperatures sometimes above 40°C during the summer months. Because of its Mediterranean climate, most of Portugal's rainfall occurs in the winter, the north receiving much more rain than the south.

Data as of 1993