Strong storms are forecast to persist through Saturday in Greece, with a slight improvement in weather expected on Sunday, according to meteorologist Nikola Ziakopoulou. The Christmas week will begin with a new wave of rain, heavy storms, and significant snowfall in mountainous areas. On Christmas Day, rain is expected to lessen, but cold temperatures will prevail due to northern winds. The article details weather conditions across various regions including Attica and Thessaloniki.