The Alentejo climate resembles the southern Californian climate. Although it is not on the Mediterranean it has such a climate, the summers are hot and dry, the winters wet and cold, and in spring and autumn temperatures are delightful, with moderate highs and lows.

Reguengos de Monsaraz area, photo by John Copland
Daytime temperatures rarely drop below 12 degrees C, but in summer it can be very hot, especially more inland.
The average lowest temperature in the coldest months, December and January, is 6ºC, and the average high in July/August, the hottest months, is 30ºC (but mercury easily can climb above 40ºC).
The climate is one of the reasons of the increasing interest of people seeking to retire to the Alentejo.