Look: Beachgoers capture sun, sea and sand - shrouded in fog

Temperatures on Saturday afternoon, September 9, peaked at 25 degrees.

The Met Office said Wales was set for a "very warm, humid, mostly dry and sunny day" - but what is behind the foggy phenomenon which has been bemusing beachgoers across the UK?

The air coming to the UK is particularly warm and moist, which condenses and turns into fog when it passes over the colder sea.

Pictures taken by Penarth Times reader Briony Goffin show a blueish mist obscuring the end of Penarth Pier.

Despite the summer temperatures, the camera could only render the sun as a blue twinkle behind the cloud.

"It was a little spooky, in a thrilling way. A bit like when it snows and everything is temporarily transformed," Ms Goffin said. "The pier disappeared into nowhere. There was no horizon between sea and sky.

"Walking on the pier was like walking on the sky."

Sam Lewis of the Vale of Glamorgan Camera Club snapped these pictures of the Knap and Old Harbour in Barry, where the mist adopted a more yellowish hue.

This picture shows the marooned vessel jutting out of the fog almost like a ghost ship.