We haven't the advantage of predictability; it may rain on any day and in any season.Tourists e.g. Americans come from places where the weather is consistent from day to day, so think that our having several consecutive rainy days in Summer must mean that it rains all the time.In fact, Nice, in the South of France, has a higher annual rainfall than London.The difference is that Nice gets torrential rain, particularly in late Autumn, but its Summer months are dry and sunny.
We get no long cold winters and no long hot summers: our minimum temperatures,in particular, bear no comparison to those of, say, New York.And we never get a 'white Christmas'!