An hour outside in Trafalgar Square, up in the air, how can you not think about the weather? For many people on the plinth this unusually wet and cold July has come in the wrong year. What I will be able to do with my work there will of course be partly determined by whether or not it rains: one o’clock in the morning is bad enough, but in a howling gale, in the dark, alone in the square, the inspiration could flag. So here, tempting fate, is the BBC’s first weather map for my night… clear over Wales and southern England. If there was a Celtic weather god, I’d be throwing things into the Thames for it now.