The dark, tsunami-like cloud formation billowed across parts of Portugal’s northern and central coasts, as the country set a heat record.

A rare roll cloud appeared over Portugal’s coast, surprising beachgoers as strong winds hit during an ongoing extreme heatwave.

Beachgoers in Portugal scrambled for cover over the weekend as the sweltering heat gave birth to a rare “tsunami roll,” or ominous wave of dark clouds over the water.