Meteorologist Nikola Ziakopoulou forecasts a significant drop in temperatures across Greece starting Sunday, with stormy northerly winds, heavy rain, and snowfalls expected, even at lower altitudes, particularly in northern regions. Friday will see mild temperatures ranging from 16 to 19 degrees Celsius, while Saturday brings anticipated rainfall and slightly cooler conditions in the northern parts. In Attica, cloudiness will be minimal, with temperatures between 10 and 19 degrees Celsius.