These two artists always remind me of summer. First is Kings of Convenience and their music makes me think of lazy summer days. Here's a song off of their latest release, Declaration of Dependence(2009).
"Mrs. Cold" - Kings of Convenience
Second is The Drums. Great band, bunch of hipsters if you ask me. They have a great sound. This single is off of their album Portamento(2011).
Hallelujah, that's the name of a single off of The Helio Sequence's album, Keep Your Eyes Ahead, released in '08. The album as a whole isn't that bad either, check them out below.