All areas of the Portuguese mainland and the Madeira archipelago start the week with a very high risk of exposure to ultraviolet radiation (UV), according to the Portuguese Institute of the Sea and Atmosphere (IPMA).
In the Azores, the islands of Flores, Faial and Terceira are at moderate risk, while Sao Miguel is at low risk.
On Tuesday, mainland Portugal and the Madeira archipelago will remain with very high levels of UV exposure.
The UV radiation scale has five levels, ranging from extreme to low risk.
For very high risk regions, IPMA recommends the use of UV-protected sunglasses, a hat, a T-shirt, an umbrella, sunscreen, and keeping children out of the sun.
IPMA recommends the use of UV-blocking sunglasses, a hat, a T-shirt and sunscreen for high-risk regions.