Markedly Mediterranean, with average temperatures ranging from 15 to 17.5ºC (59 to 63.5 ºF), with large daily temperature ranges (hot days and cool nights) and long, hot and dry summers where the maximum daily temperature normally exceeds 35ºC (95ºF). Winters are cool and can even reach below zero (32ºF) temperatures at night.
Average annual rainfall is around 600 mm (23.62 in), ranging from higher average values in the north of the region - 800 mm (31.5 in) in Portalegre, and minimum values of 500 mm (19.69 in) in Moura, in the south (interior) of the region. In general, rain is practically nonexistent during the period from May to late September, thus ensuring that the grape harvest will take place in dry weather (mid-August to late September).
Insolation is one of the highest in Europe (a total of 3 000 hours per year), especially during the months before and during the grape harvest, thus guaranteeing adequate maturation, which helps generate sugars and colouring matter.
The Alentejo is essentially a collection of vast undulating plains, but there are also orographic features – the main ones are the Portel (421 m), Ossa (649 m) and S. Mamede (1025 m) mountain ranges – which help create microclimates which have an impact on wine production.
