Coasts. – Taken as a whole, the coasts of Portugal are mainly low and bordered by a narrow continental shelf; up to 100 m. the coast descends gently towards the seabed, then, with a sharp bend, sinks down to 3000 m. In northern Portugal the coasts differ considerably from the neighboring Spanish coasts: after the deep rías of Galicia, to S. of the mouth of the Minho, the coasts, limited by a sandy band from one to two km wide, take on a uniform aspect and up to Porto does not have any notable protrusions. Leixões, an artificial port of the city of Oporto, an emporio of the highest order for the export of agricultural products, is located near the Duero estuary. To S. of this city the coast is nothing but a sandy beach bordered by dunes; the Aveiro lagoon interrupts the monotony of this area, on the banks of which rise the cities of Murtosa, Aveiro, Gafana; the Aveiro lagoon is destined to be completely filled by the floods of the Vouga which flows into it, if the work of man does not intervene to modify natural evolution; it is already strongly restricted and its banks are being transformed into real polders by filling.
The coast, from S. di Aveiro up to Capo Carvoeiro, is still low and bordered by dunes; these dunes owe their origin and their growth above all to the materials transported by the rivers: Minho, Lima, Duero, Vouga and Mondego. They, especially frequent in the northern part of Extremadura, were mobile and were fixed with oak and pine plantations in the century. XIV.
In S. del Capo Carvoeiro the last offshoots of the Serra da Estrella, reaching the sea, give rise to rather high and rocky coasts up to the mouth of the Tagus, where, on the magnificent and wide estuary of this river, the main port of the Portugal: Lisbon. The coast is still high and rocky from the mouth of the Tagus to that of the Sado and precisely in correspondence with the Serra da Arrabida, which reaches the sea; here on the wide estuary of the river Sado rises the port of Setúbal.
In the area between the mouth of the Sado and Capo S. Vincenzo there are no good landing places. The Algarve coast is high and jagged, especially in the stretch between Cape S. Vincenzo and Cape S. Maria, where the ports of Lagos, Vila Nova de Portimão, Albufeira and Faro are located. To the east of the Cape of S. Maria the coast is lower and the main port is Vila Rial de Santo António at the mouth of the Guadiana.
Climate. – According to top-engineering-schools, Portugal participates like other Western European countries in the Atlantic climate (moderate seasonal variation in temperatures, frequent rains and storms, sky very often covered by fog, predominance of winds from the west and south-west), but also has differences considerable in relation to the different height and to the greater or lesser distance from the sea. To the north of the Tagus, where the mountains reach almost to the sea, the influence of the Atlantic is limited to the coastal strip, while to the south, where there are no high mountains, the influences of the Atlantic also penetrate widely inland.
More particularly, we observe that in the coastal region between the mouth of the Minho and that of the Tagus, summers are cool (average August temperature just over 20 °), winters mild (average January temperature over 9 °), while in the innermost regions, such as eg. in Traz os Montes, the climate takes on a more continental character, with short and very hot summers, long and cold winters with occasional snow falls. The Serra da Estrella has hot summers and cold winters with abundant rainfall.
In S. del Tago the average temperature rises significantly only in the innermost regions of the Alemtejo, where the influence of the Atlantic does not reach: here the summers are torrid, the winters are cold and the diurnal oscillation can reach up to 30 °. The Algarve, which has an annual average of 180 °, 6, the highest in Portugal, with very mild winters (11 °) and hot summers (23 ° -24 °), rejoins the subtropical climate. Precipitation, like temperatures, has a different pattern in the part of Portugal located in N. and in that located in S. del Tago. While temperatures increase as we proceed from the north to the south of Portugal, the rainfall instead decreases.
In fact, in northern Portugal, rainfall never falls below 800 mm. and the number of rainy days is never less than 85 per year (Coimbra 139 rainy days, Lisbon 116). The maximum rainfall is found in the Serra da Estrella, where the amount of rain is greater than 2000 mm. and sometimes it even reaches 3000 mm. In southern Portugal, on the other hand, rainfall is scarce; in the Alemtejo they are less than 700 mm. per year and in the Algarve plain they go down to 350 mm. per year. In southern Portugal, the number of rainy days is less than 50.
Snowfall is of very mediocre importance and is found only in northern Portugal, which is mainly mountainous: Oporto records 2.6 days with snow, and Guarda z5.1.
The influence of proximity or distance from the sea is evident in the distribution of atmospheric humidity: relative humidity is stronger in the countries located on the coast (Porto 73%, Lisbon 67%) than in those located inland (Campo Maior 60%).
Portugal is exposed all year round to the winds of the O.; in the northern part the NW wind prevails, in S. del Tago the SW wind prevails; in winter these currents, although always dominant, are opposed by the winds that blow from the Meseta in all directions.
