The Dry Season

There are pros and cons of when you visit the park. We came after Labor Day so the infamous summer crowds were gone. I can't imagine Yosemite in July. That said, you lose one of the iconic waterfalls that make Yosemite famous if you come in the summer or early fall.
Behind me should be a huge waterfall but naturally it's the dry season.
I understand it's best to come in the early Spring when nature's faucets are running at full power.

Here is a site that gives you a good idea of what it looks like when the water is flowing.

http://trifter.com/usa-canada/magnificent-waterfalls-of-yosemite-national-park-2/