A guy lives in the 10th floor of an apartment building. On a normal day he goes to the 5th floor with the elevator and then climbs the remaining 5 floors. On a rainy day he goes to the 10th floor directly.
Why ?
I think:
He is a short person, so he can't reach the button, when it's raining he has his umbrella to push the button for him
Another possibility :
He prefer to take the stairs instead of the elevator. On his building stairs start only on 5th floor, are outside and aren't protected of rain. When the weather is ok he stops on the 5th floor and takes the stairs, but when it's raining he prefer to be dry and go directly on his floor.