I really like the overall story of this poem. I know that a lot of people write about summer, and too often it ends up being cliche. You managed to avoid the cliches really well. I like your metaphors and similes; they are fairly original.
Some places where you could do better are some of your sentence structures. This may just be a personal preference, but "Our hearts are tiny mechanical rabbits pitter-patter-pitter-pattering beneath the bumpy jump of skin and bone and they are the strongest part of our body and that is why we follow them despite their silly rabbit feet" could be broken up into two sentences at "they are the strongest...". Up to you. There's a few other places in this poem where you seem to have a run-on sentence going. I don't know if that's intentional. I also think that the second "pitter" and "patter" could be taken out--I think it might make the flow better. Again, that's up to you.
Good story. Good language. Work on your flow and style a little bit. I'm available for a message if you'd like more advice. :)