The warning is place until 9am Friday according to the Portuguese Institute of the Sea and the Atmosphere (IPMA).

The IPMA forecasts for today on the continent, clear or cloudy skies and light to moderate winds from the east, but moderate to strong in the highlands.

The forecast also points to the formation of frost, especially in the interior and the possibility of morning fog in some places.

The minimum temperatures will fluctuate between -1 degrees Celsius in Bragança and 7 in Porto, while the maximum between 9 in Guarda and 18 in Braga.