Fun fact: the optimal weather for cleaning windows is actually a dry and cloudy day, since the cleaning solution can dry quickly on a sunny day, leaving streaks that are hard to remove on the windows. Experts also recommend using microfiber cloths to dry the windows.
I have had my second floor windows cleaned a couple of times already. They are so quick and efficient. I come home and it was like nobody ever came by. Only way I know they were there, is the beautiful...