Mainland Portugal faces on Saturday, September 5th, a day of strong meteorological contrasts, with intense heat being felt while thunderstorms, rain and hail approach the territory. According to Meteored's forecasts, this will be the most unstable day of the weekend, with temperatures that could approach or reach 40°C in regions such as Bragança, Castelo Branco, Évora and Beja. Santarém could reach 37°C and Lisbon 35°C, while the North and Centre coast, under maritime influence, will have considerably lower temperatures, with Porto and Aveiro among the cities least affected by the heat.
It is during the afternoon that the meteorological situation should worsen, with instability beginning in the northern interior and subsequently spreading to the central interior. The thunderstorms should cover a vast area, developing from North to South of the mainland territory, with greater activity expected in the North and Centre, where a high concentration of lightning strikes is forecast. Some showers could be moderate to heavy during short periods, with accumulations that locally could approach 8 mm in one hour. Localized occurrence of hail and strong gusts is not excluded, resulting from strong heating near the surface combined with colder and more unstable air at altitude.
Sunday brings a significant change in the weather, with instability losing expression and showers and thunderstorms ceasing to be protagonists. The heat begins to ease in several regions, with values close to 40°C no longer forecast. In Porto, the maximum could be around 23°C and in Aveiro around 22°C, while Lisbon should be around 30°C and Castelo Branco around 35°C. The temperature drop will be particularly evident on the North and Centre coast, while in the southern interior the heat will continue, although without the extreme values of previous days.
Monday and Tuesday should maintain a similar scenario to Sunday, with greater atmospheric stability and a marked contrast between the cooler coast and the still warm interior. The meteorological models do not anticipate, for now, a new significant episode of instability in these first days of the week. After a Saturday marked by heat, showers, thunderstorms and possible hail, Portugal should enter a phase of drier and more stable weather, although forecasts may change as the period in question approaches.
