The Hellenic National Meteorological Service (www.hnms.gr) on Tuesday issued a warning of a sudden shift in predominantly warm and sunny weather, starting in the early hours of Wednesday in the northwest of the country and gradually spreading south and east.
The first heavy showers will be experienced in the northern Ionian, in Epirus and western parts of the Greek mainland on Wednesday morning. Storms are forecast later in the day in the southern Ionian, the Peloponnese, the islands of the Cyclades, Eastern Macedonia, Thrace and the islands of the northern and eastern Aegean, where they will continue into Thursday.
The HNMS also said that strong northerly winds will bring a significant drop in temperatures across the country.
In Attica, clouds will begin to gather in the afternoon on Wednesday, bringing brief localized showers and thunderstorms. Temperatures are expected to range between 14-26 degrees Celsius.
In Thessaloniki, some fog is forecast in the early hours of Wednesday, with localized showers and thunderstorms later in the day. Temperatures will also range from 14-26 degrees Celsius.