Mainland Portugal will face a significant weather change over the coming days. First, a very hot air mass from North Africa will advance over the Iberian Peninsula, raising temperatures from Wednesday onwards. The heat peak is forecast for Thursday, September 3rd, with the interior exceeding 35°C and locations in the Alentejo, such as Évora and Beja, potentially reaching or exceeding 40°C, with peak highs around 42 to 43°C. The Centre and North regions will also be affected, with Santarém and Castelo Branco approaching 39°C.
On Friday, September 4th, the heat begins to lose intensity in the Alentejo, with a drop of four to five degrees, although the environment remains warm. In the opposite direction, the northeastern Trás-os-Montes region and the Douro valley may reach 40°C again. It is also on this day that the first signs of weather change appear, with increased cloud cover and the possibility of weak, scattered precipitation.
The most significant change is forecast for Saturday, September 5th. Projections from the European ECMWF model analyzed by Meteored indicate showers and thunderstorms, especially in the interior of the North and Centre regions. The combination of hot air at the surface with the arrival of colder air at altitude should increase atmospheric instability, favoring the formation of tall cumulonimbus clouds and particularly intense electrical activity between Vila Real, Viseu and Guarda.
The most intense cells may bring hail and strong wind gusts, especially during Saturday afternoon. However, the precipitation distribution tends to be quite irregular in this type of situation, with heavy rain in one location while practically no rain falls a few kilometres away. The forecast remains subject to changes, as small changes in atmospheric conditions can significantly modify the location of the most intense cells.
