Enormous hail storm in August!

[pjbw]

At about 3pm on Thursday 23 August 2018 here near Lisburn in Northern Ireland I heard heavy rain on the roof.

At about 3:05 this turned into the biggest heaviest downpour that I have ever experienced. It was hail, deafeningly noisy and it  became impossible to see out through the windows. No wind but I was afraid that it would damage our cars.

Then the hail stopped as suddenly as it had begun at about 3:07. It was slushy, hadn't damaged the cars and hadn't lain in the lawn. My barometer had not noticed anything unusual and at about 3:10 the sky cleared and the sun came out.

What could have caused this?

In all my 80 years of flying, sailing, etc. I have never known anything like this; hail, August!

[Paul]

Hail in August really isn't that rare, it can occur anytime there are strong convective updrafts, regardless of the time of year. Even at the peak of summer, the air temperature still falls with height, so if the updraft is high enough, it'll reach a point that's sub-zero