The climate in Portugal is not unlike what you will find elsewhere in the Mediterranean — temperate, but without the extremes seen elsewhere on the continent. It is one of the warmest European countries, but the cooler waters of the Atlantic Ocean tend to tamp down the heat that one encounters further inland on the Iberian Peninsula. The western parts of the country have a more maritime climate with cooler, dry summers; the southern regions a more Mediterranean climate with warm, dry summers.
Portugal’s winter: December to February
Portugal’s summer: May to September
Average annuals temperatures on the mainland range from 8–12 °C (46.4–53.6 °F) in the mountainous interior of the north, where temperatures depend more on elevation than latitude, to average annual temperatures as high as 20 °C (68 °F) in places such as the Guadiana Basin. Extreme high temperatures of more than 40 °C (104 °F) are not all that uncommon during the summer months in southern Portugal. Average annual humidity is around 85%.
The Algarve Region experiences some of the best weather in Europe, if not the world. Offering a shocking 3,300+ hours of sunshine per year, Algarve gets more sun than nearly any other destination in Europe. World Weather Online states that the “Algarve enjoys one of the most stable climates in the world.” Overall, Portugal has around 2500 to 3200 hours of sunshine a year, an average of 4 to 6 hours during the winter months and between 10 and 12 hours in the summer. Generally, the south-east tends to be sunnier than the northwest.
Ocean temperatures in Portugal
Ocean temperatures at the surface on the west coast of mainland Portugal vary from between 13 and 15 °C (55.4–59.0 °F) in winter to 18–22 °C (64.4–71.6 °F) in the summer. On the south coast, it ranges from 15 °C (59.0 °F) in winter to about 23 °C (73.4 °F) (sometimes slightly higher) in the summer.
Precipitation in Portugal
Rain in Portugal also depends largely on latitude, with the northern regions getting the bulk of it on an annual basis. The northern mountains might get as much as 126 inches of rain in any given year, while the more arid south can see as little as 12 inches a year. The average across the entire country is 25 inches of rain per year. Snow falls are regular in the upper altitudes of the northern and central parts of the country, namely Vila Real, Bragança, Viseu and Guarda where winter temperatures can drop as low as −10.0 °C (14.0 °F). Snow can fall anytime between October and May in these areas. Snowfall in the south is rare, but can occur at higher elevations.