Évora, Faro, Setúbal, Beja and Portalegre will be under an orange warning due to "persistent high maximum temperature values" between midnight on Saturday and midnight on Sunday.

These five districts will be under a yellow warning between 9:00am on Friday and midnight on Saturday.

Between the same time on Friday and midnight on Sunday, Bragança, Viseu, Guarda, Vila Real, Santarém, Lisbon and Castelo Branco will be under a yellow warning due to the hot weather.

Porto, Viana do Castelo, Leiria, Aveiro, Coimbra and Braga will be under a yellow warning between 9:00 am on Saturday and midnight on Sunday.

The orange warning, the second most serious on a scale of three, is issued by the IPMA whenever there is a "meteorological situation of moderate to high risk," and yellow, the least serious, when there is a risk situation for certain activities dependent on the meteorological situation.

The IPMA predicts a gradual rise in temperatures of around 10 degrees Celsius from today until the weekend, with maximum temperatures above 40 degrees in some regions.

According to the Institute, the weather in mainland Portugal and the Madeira archipelago will be influenced by an anticyclone that is expected to position itself north of the Iberian Peninsula and a depression that will give rise to the approach of a mass of hot air coming from North Africa.

On the mainland, the temperature will register a gradual rise, with the highest values ​​starting on Saturday, when they should vary between 35 and 40 °C in most of the territory, with the exception of some areas on the north and central coast, and values ​​between 40 and 44 °C in the south, Tagus valley and Douro Valley.

The minimum temperature will register values ​​close to 20 °C in a large part of the territory, especially in the southern region, where it may not drop below 25 °C in some places, namely on the Algarve coast and the Portalegre region.

The IPMA also predicts the presence of dust in the air in the southern region from this afternoon, extending to the rest of the country in the following days.

In the Madeira archipelago, the maximum temperature will also rise gradually over the next few days, with the most significant rise recorded in the highlands of the island of Madeira, where values ​​between 26 and 28 °C are expected on Saturday and Sunday.

The minimum temperature, on the south coast and on the island of Porto Santo, should not be below 20 °C, which is designated as tropical nights.

On the north coast and in the highlands, the minimum temperature should vary between 14 and 18 °C.

According to the IPMA, the duration of this episode of hot weather remains uncertain; however should continue until the beginning of July, especially in the southern region.