The Portuguese Institute of Sea and Atmosphere (IPMA) has placed under yellow warning due to high temperatures the districts of Setúbal, Santarém, Lisbon, Leiria, Coimbra and Braga.
The warning extends until 18:00 on Sunday for the districts of Faro, Beja, Evora, Portalegre, Castelo Branco, Guarda, Vila Real and Bragança.
On Wednesday, after a meeting with the Minister of Internal Administration to assess weather forecasts for the coming days, the IPMA president warned that the country would go through a third heat wave from Saturday.
After this alert, the Directorate General of Health (DGS) recommended the adoption of additional protective measures against heat, such as increasing water intake or fruit juices and advised the population to avoid drinking alcoholic beverages, as well as direct exposure to the sun, especially between 11am and 5pm.
In a note posted on the website, the DGS also advises people to seek fresh and airy environments.
The use of clothing covering most of the body, a wide-brimmed hat and sunglasses with ultraviolet protection are additional protective measures recommended.
The DGS also advises the population to avoid "activities that require great physical effort, namely outdoor sports and leisure activities".
It also recommends choosing the less hot hours for travelling by car and calls for special care for the most vulnerable groups, such as children, the elderly, the chronically ill, pregnant women, people with reduced mobility and outdoor workers, etc.