Contrary to popular belief, 'cast not a clout till May be out' is nothing to do with hitting people. It is not saying that the Open Season for Punching begins on May 1st. The 'clout' referred to is 'cloth', or clothing. Those of you who studied Romeo and Juliet at school may remember that the nurse compares Paris favourably with Romeo: 'Oh, he's a lovely gentleman. Romeo's a dishclout to him.' As in dishcloth.
The 'May' referred to is not the month, either. It's the may blossom, or hawthorn. So the saying means, don't start flinging the layers off until the hawthorn blossom is out. These days this tend to be April, or earlier. It's not out yet. The wild plum is in bud, and that's usually the first to burst into blossom in England. Another couple of days like today, and the hedgerows will be sugared with pink and white, and our hearts can unclench.
A blue true dream of sky, but no leaping greenly spirits of trees yet. The weeping willows are golden on the far side of the pool, as you can see. But it was so warm! I saw a lass in sandals. People were peeling off coats and jumpers. I was in my customary winter wear of treggings, boots and big cardigan and I was regretting my merino wool base layer. Maybe with global warming we'll have to rewrite the old saying: 'Do not remove your thermals until the wild plum is in blossom.' Nah, it doesn't have the same ring, does it?