The nursery rhyme originates from Britain, probably the north of England. For those who don't know, rain is a regular feature of the British Isles. On average, it rains for 133 days a year - when it's not snowing or foggy - producing an average of 885 mm of rain.
That's the average. Some parts of Britain, such as the Scottish Highlands, Snowdonia and the Lake District see more than 4 metres in a year.
There have been reports of Doctors falling into puddles in Gloucester, as well as old men going to bed to miss the weather.