The National Observatory of Athens said over 10,000 thunderbolts occurred throughout Greece in 12 hours on Sunday, according to their ZEUS monitoring system.
According to the Observatory the combination of hot and liquid masses with the high atmospheric instability over Greece accounted for the large number of thunderstorms.
The evening thunderstorms in Greece in June are natural due to the high instability observed every year, according to the Observatory's meteorological service.
However, it is not frequent to be accompanied by large sized hailstones up to 5-6cm, as it happened in many cases on Sunday mostly in the regions of Ioannina, Pella and Kozani.
