A hot and humid day in Durban changed dramatically after being engulfed by a giant wet wave.

Bluff ripper Ricky Basnett spotted it from his porch overlooking Cave Rock, and snapped this image as it bore down on the city.

Meanwhile, a little further north of Durban, goofyfoot charger Mike Frew was still being bathed in sunshine when he took this picture of the roll cloud tumbling over the Golden Mile.

Interestingly, Wikipedia describes roll clouds as a ‘wave that has a single crest and moves without changing shape and speed.’

And what a wet wave it was. Surfers still out in the lineup were using their boards as a shield from the hail, and buckets of rain drenched the city in a matter of moments.

Roll clouds are in fact one type of Arcus cloud, which aren’t particularly common, and it’s hard to predict when next a marvellous set like this will roll through Durban’s cityscape.