A strong cold front moving in from the northern Balkans is expected to bring severe thunderstorms, heavy hail and flash-flood risk across much of Greece on Friday, meteorologists said.
Klearchos Marousakis, chief meteorologist for Open TV, said that Friday will be the most dangerous day of the week, with clear weather in the morning giving way to rapid instability by early afternoon.
Mr. Marousakis warned of torrential rain, intense lightning and localized hail as the system pushes south.
The storms are expected to hit northern and northwestern Greece first before spreading across the central mainland, the Peloponnese and the western Aegean.
Emergency services have been placed on alert, particularly in mountainous and semi-mountainous areas vulnerable to sudden flooding.
In Attica, temperatures are forecast to reach 34 degrees Celsius before conditions deteriorate in the afternoon.
Strong northerly meltemi winds are also expected in the Cavo D’Oro shipping strait, with gusts reaching 7 Beaufort.
Thessaloniki is also likely to see unstable weather, with daytime highs around 33 degrees Celsius.
Forecasters said the system should begin to clear late Saturday, bringing a brief drop in temperatures to around 30 degrees Celsius nationwide.
But the relief may be short-lived. Mr. Marousakis said a new high-pressure system is expected to build next week, sending temperatures climbing again and possibly pushing inland readings toward 37 degrees Celsius.