BBC weather forecast - NOT amateur radio

Last Friday my wife booked for us to visit our nearby National Trust property. When she booked the BBC weather forecast full sun. When we left home it had already changed to light cloud. Now we are home it has changed again with a strong likelihood of rain soon. Honestly they really haven't a clue. Unless there is a big high pressure system it would appear their super computers do little good. Frankly they are a joke.