As for fog, especially in valley areas, the four districts will be under warning until 12:00 on Tuesday, according to the IPMA, which warns of the formation of icicles.

The institute also issued a yellow warning for those four districts due to the cold weather with persistent low minimum temperature values, between 01:00 today and 10:00 on Wednesday.

This orange warning is issued by IPMA whenever there is a moderate to high risk meteorological situation and yellow when there is a risk situation for certain activities depending on the meteorological situation.

The IPMA predicts light or clear skies for today on the continent, appearing very cloudy in the northeast of Trás-os-Montes and Beira Alta, a generally weak wind from the eastern quadrant, mist or morning fog, especially in the northeast of Trás-os-Montes and Beira Alta.

Frost formation is also expected, mainly in the interior and a small drop in the minimum temperature in the North and Central regions.

Minimum temperatures will range between -5 degrees Celsius (in Guarda) and 08 (in Faro) and maximum temperatures between 05 (in Vila Real) and 17 (in Faro).