The weather service warned that temperatures will drop significantly in the next 24 hours in Greece, with sleet and high winds expected for most of the country, and snow forecast for the mountainous and northern regions.
Snowfall is expected in the northern parts of Athens.
In Thessaloniki temperatures will fall to -5 degrees. Winds will reach 8 on the Beaufort scale.
Meanwhile, the municipal services in Athens announced that several community centres will open to serve homeless people.
Snowfall and freezing temperatures have hampered traffic in some parts of the country as a result of the new wave of bad weather that has hit Greece.
Cars moving on Parnitha Avenue will need snow chains on Thursday. The ferry service from Rio to Antirrio, linking the Peloponnese with the mainland, remains closed because of strong winds blowing in the area. Strong winds also led to cancellation of boat schedules from the Attica mainland to and from the Saronic Gulf.
In northern Greece, the Kavala-Prinou and the Keramoti-Thassos port schedules have also been cancelled.