The districts of Viana do Castelo, Braga, Porto, Aveiro, Coimbra, Leiria and Lisbon will have the warning in place until 18:00 today.
The yellow warning is issued by the IPMA whenever the weather situation represents a risk for certain activities.
As for the general weather, the IPMA forecasts for today on the mainland, light cloud cover becoming denser as the day progresses with the possibility of rain in Minho, gradually extending to the rest of the North region.
The forecast also points to the possibility of fog or morning fog in some valleys and lowlands and frost formation in some places in the northeast of Trás-os-Montes and Beira Alta.
The minimum temperatures will fluctuate between 01 degree Celsius (in Bragança) and 10 (in Faro) and the maximum between 16 (in Guarda) and 21 (in Évora and Leiria).