Today started out as one of the most beautiful of the year so far. I went walking with a friend and our dogs on Portmarnock beach in the early afternoon. It was magnificent.

Then around 3.30 the sunshine started to disappear into a fog that has become denser and colder over the last few hours. As far as I know it’s called a sea fret, a curious phenomenon that is caused by the cold air over the sea meeting the warm air over land.

Visibility along this part of the Dublin coast has been pretty non-existent these last few hours.