In a statement, the Portuguese Institute of the Sea and Atmosphere (IPMA) said the hot weather episode is "expected to continue until August 6, with a high degree of confidence," although with a slight temporary drop in maximum temperatures on Friday on the west coast and, possibly, on Tuesday.

The IPMA states, "maximum temperatures will be above average, or far above average, for the time of year," meaning it is "very likely" that a heat wave will actually be experienced in much of mainland Portugal, particularly inland areas.

"This episode of hot weather is expected to be considerably severe, both due to its duration and the very high maximum temperatures," the IPMA warns, indicating that starting Sunday, high temperatures are expected to range between 36 and 40 degrees Celsius, with the exception of a few areas along the coast, where they will be lower.

In the inland Alentejo, the Tagus Valley, and most of the inland part of the Douro Valley, high temperatures are expected to reach between 41 and 44 degrees Celsius.

Furthermore, the IPMA adds, "tropical nights are expected across most of the country," with low temperatures ranging approximately between 20 and 25 degrees Celsius starting Monday.

Based on the forecasts, the IPMA has already placed all districts in mainland Portugal, with the exception of Faro, under an orange warning between 9:00 a.m. and 6:00 p.m. on Sunday, due to "persistent high maximum temperatures."

Until Sunday morning, the 17 districts—Bragança, Viseu, Évora, Porto, Guarda, Vila Real, Setúbal, Santarém, Viana do Castelo, Lisbon, Leiria, Beja, Castelo Branco, Aveiro, Coimbra, Portalegre, and Braga—will be under a yellow warning, also due to high maximum temperatures.

The district of Faro will be under a yellow warning between 9:00 a.m. on Saturday and 6:00 p.m. on Sunday, also due to persistent high maximum temperatures.

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