The climate of southern Portugal is typically Mediterranean, with a hot and dry summer alternating with a relatively cold and rainy winter. However, the influence of the geographic situation determines the existence of a high number of climatic conditions that give rise to particular characteristics of each region.
The annual average relative humidity is between 75% and 80%, which reflects the region's proximity to the sea, with lower values in the summer months, especially during the hottest hours. The dominant winds blow from the North, Northwest and West quadrants with average speeds of 11 km/h
The region presents high insolation values (number of hours of sunshine) - 220 hours - with summer values above 300 hours of sunshine per month.
The average annual precipitation values vary between 550 and 750 mm, with a distribution throughout the year similar to that of the country, with the months of June to August being the ones with the greatest water deficit, also due to the reduced water retention capacity of the soils. .
In terms of temperature, relatively high values are recorded in the months of summer (25 to 28 ºC), being at zones in new sales it's from
Alcácer do Sal the hottest, with average temperatures that can reach values close to 30 ºC.
In these two zones there are greater thermal amplitudes, mainly in summer, due to the influence of continentality that already exists there, marking the respective climates.
In terms of frosts, these occur more frequently in the months of January, February and December. However, in the areas of fortress of salt and
mainly in Vendas Novas there are still occurrences of frost in the months of March and April, with values of around 4 days of frost per month, which can cause problems in the cultivation of the vine since this, at this time of year, is in phases. initial buds, at a time quite sensitive to the occurrence of burning due to frost.
According to Koppen's classification, the region's climate is of the Csb type: temperate climate with rain and no regular snowfall; average amount of precipitation in the driest month less than a third of that of the wettest month and less than 40mm; dry season in summer with average air temperatures above 22°C in the hottest month (there are more than four months when they are above 10°C) and between 0 and 18°C in the coldest month.
Lithological and pedological characterization
The region is quite homogeneous in geological terms, having only Pliocene and Pleistocene sedimentary formations, which correspond to sands, rolled stones, sandstones and clays. These materials gave rise to light textured soils with varying degrees of evolution.
In pedological terms, the most frequent soils in the region are the Podzois (PZ). These dominate in the areas of Alcácer do Sal, Moita, Palmela and New Sales. They are relatively deep soils, with a very light texture and low content of organic matter in the superficial layers, because due to the intense leaching it migrates to lower horizons, where it accumulates and can form impermes. In the first 50 cm the soil is very poor in minerals, has an acidic pH and a very low field capacity. (Cardoso, 1965). These characteristics lead to accentuated water deficits in the summer months.
Thus, it is verified that the soils of the region are, for the most part, of light texture (sandy), with a relative heterogeneity, with variations in texture (soil patches) being found in short areas, with zero or very low aggregation, poor in minerals, with a relatively acidic pH ( 5 to 6 ) and with low water retention capacity.