I’ve just looked up the weather for the next few days. What is the difference between “mainly fine” and “partly cloudy”? There must be a certain percentage of cloud cover at which the definition switches over. Like “occasional shower” as opposed to “light rain”.

Of course it could be the far more likely hypothesis. At this time of year they figure it’s probably going to be cold, and there’s a chance of some kind of moisture in the air. Pick a temperature reading below 20 degrees celsius, coin a moist sounding phrase, and then sell the information as a weather report. Easy. For those who’re wondering, my random weather phrase generator predicts tomorrow will be about 17 degrees celsius with a chance of an occasional shower, although mostly fine when not raining.