Temperatures fell to minus 10 degrees Celsius (14 degrees Fahrenheit) in Milan on Monday as 59,000 households remained without electricity in Italy and officials declared a gas supply emergency.
"The situation is certainly critical because the flows from Russia and France have diminished but the situation is being monitored," Economic Development Minister Corrado Passera told reporters.
The death toll from the rare cold snap in Italy meanwhile rose to 17, with eight deaths reported on Sunday including three homeless people found in the seaside town of Ostia near Rome and at the capital's train station.
A 37-year-old Sri Lankan migrant was also found dead in a shack in Tuscany.
Snow began falling in the outskirts of Naples and snowed-in villages around Rome began organising soup kitchens because of the power outage.
Schools and public offices in the Italian capital also remained closed.
The Abruzzo region declared a state of emergency and the army sent 530 soldiers and 90 snow ploughs and bulldozers to clear the roads. There were also major traffic delays in the the port of Ancona and the Marche region.
A Greek ferry with 360 passengers, 160 trucks and 70 cars on board which arrived in Ancona on Sunday had still not unloaded because of the conditions.
The Tuscan cities of Siena and Arezzo, where a total of 36,000 households have been without power for days, said they were considering lawsuits against Italian power giant Enel.