According to the IPMA, the districts of Viana do Castelo, Braga, Porto, Aveiro, Coimbra, Leiria and Lisbon will be under yellow warning due to the sea turbulence, with northwest waves ranging from 4 to 4.5 metres.
Viana do Castelo, Braga, Porto, Aveiro, Coimbra and Leiria will be under yellow warning until 6pm Friday and Lisbon between 12am and 6pm Friday.
The yellow warning, the third on a scale of four, indicates a risk situation for certain weather dependent activities.
Alongside these warnings, seven mainland and Azores sea bars are now closed to navigation and seven others are conditional.
According to the Navy, the bars of Esposende, Póvoa do Varzim and Vila do Conde are now closed to navigation because of the sea turmoil.
The bars of Viana do Castelo, Aveiro, Figueira da Foz, Sao Martinho do Porto and Lagos, on the mainland, and Santa Cruz das Flores and Lajes das Flores, in the western group of the Azores, are conditioned.
The forecast also points to the occurrence of periods of rain, generally weak. From the morning, more frequent and intense showers on the coast, this may occasionally be hail and accompanied by thunderstorms in the northern regions of the Montejunto-Estrela mountain system.
Snowfall is also expected at the highest points of Serra da Estrela from early in the morning, gradually lowering the altitude to 1200/1400 metres throughout the day.
The IPMA also predicts moderate west-northwest wind, blowing moderate to strong northwest, west coast and highlands, sometimes gusting up to 65/75 kilometres per hour and slight drop in temperature.
In the southern region, it is expected to have cloudy periods, being cloudy until early morning and periods of light rain and drizzle, becoming cloudy in the leeward Algarve from mid-morning and in the interior of Baixo Alentejo from afternoon.
There may also be light showers starting in the afternoon on the Alto Alentejo and west coast.
The wind will blow faint to moderate from the west quadrant, drifting to moderate northwest from the morning and becoming moderate to strong on the west coast and highlands, sometimes gusting up to 60 kilometres per hour and morning fog in some locations is also predicted.
The minimum temperatures will range from 2 degrees Celsius (in Guarda) to 13 degrees (in Lisbon) and maximum temperatures from 9 degrees (in Guarda) to 19 (in Faro).