The combination of warm temperatures and high humidity levels will bring strong downpours and hailstorms to many parts of Greece this week, the national weather service has warned.
The unsettled weather will be most intense in the mainland area on Monday and Tuesday – more so during the afternoon hours – petering off by Thursday afternoon, with western parts expected to be hit the hardest.
Evia and the islands of the Aegean should also expect some rain and a few isolated storms.
Athens and the northern port city of Thessaloniki will be hot and muggy for most of the morning on Monday and Tuesday, with overcast skies turning into storms later in the afternoon and easing at night.
The daytime highs will 28 degrees Celsius, inching up to 31C through Friday, in both cities.
People who are sailing or camping are advised to check local weather forecasts, especially for lightning or hail.