No more rain!

I used to enjoy the rain in springtime -- it was a nice reprieve from the heat that seems to come so quickly. Now, however, I've got a toddler who doesn't understand the simple equation rain=stay inside, or at least it does in my book.
She's pounding on the door and looking outside and doesn't understand why we can't just go play in the rain. After the muddy mess I cleaned up last week, I'm not quite ready to go there again, not yet.

Here's what I don't get. It's cloudy and raining on my side of the hill, and bright and sunny on the other. How does this happen?