From the BBC
Lightning strikes in several European countries have killed one man and caused serious injuries as summer storms hit across the Continent.
The man was killed in southern Poland as he was hit by lightning while descending a mountain.
Analysis, by Clive Mills-Hicks, Meteorologist, Met Office
The storms developed because a very warm and humid air mass covered mainland north-west Europe at the same time as the air higher up in the atmosphere was becoming colder, creating a very “unstable” atmosphere.
This instability manifested itself in the storms which developed extremely rapidly once the air had warmed up sufficiently.
Over much of the area, the temperature climbed to 25 Celsius, more than enough to trigger the storm clouds. Such storms produce intense rainfall, hail, and numerous lightning strikes and it is typical for them to be at their most widespread and intense in the early afternoon. They are not unusual over the Continent during the summer, although today’s outbreaks were perhaps more widespread than normal.
This tallies well with what I have observed these past few years.