Portugal is a country that has 2 main seasons weather concerning. The temperatures in summer can get as high as 40ºC and in winter usually are around 15ºC on the coast.
As far as the wind the normal directions are from North in summer due to the wind circulation caused by the center of high pressure located in Azores. This high pressure causes strong winds on the costal flying sites during August. There is around 20% to 30% of flying days during this month. The remaining summer months are far better to fly and have around 50% of flying days. Inland, during summer, Portugal has excellent conditions for thermal and cross-country flying.
The best time to fly around the coast is Autumn, Winter and Spring. In these months the weather pattern is determined by the passage of cold and hot fronts that make the wind turn from south to west. Around Lisbon there are a number of places to fly with these directions and there are around 70-80% of flying days.