Six areas are under yellow warning for high temperatures on Tuesday, and four more areas will join the list on Wednesday, according to the Portuguese Institute of the Sea and Atmosphere (IPMA), which will keep the warnings in place until Thursday.
The areas of Bragança, Évora, Guarda, Beja, Castelo Branco and Portalegre are under warning from 00:00 to 18:00 on Thursday.
On Wednesday, the warning will extend to the areas of Porto, Vila Real, Viana do Castelo and Braga and will remain in effect until 6:00 p.m. on Thursday.
A yellow warning, the least serious of the three, is issued whenever there is a risk to certain activities due to weather conditions.
On Tuesday, the west coast will be cloudy in the morning, with a chance of rain. Winds will be strong at times along the western coast and in the highlands. Temperatures will fall slightly inland and maximums will rise slightly in the eastern Algarve.
The areas of Castelo Branco and Evora are expected to be the hottest with maximum temperatures of 39 degrees Celsius, while Aveiro is expected to be the coolest with 24 degrees.