Half way only in lift

There is a man that lives on the top floor of a very tall building. Everyday he gets the elevator down to the ground floor to leave the building to go to work. Upon returning from work though, he can only travel half way up in the lift and has to walk the rest of the way unless it's raining! WHY?

Answer:

The man is very very short and so can only reach half way up the liftbuttons! However, if it is raining then he will have his umbrella with him and so can press the higher buttons with it.