"Fly By Day Viva California Time." This song by Anri, off of her Heaven Beach album, is warm, soothing, with sounds of the seashore glittering in the background.
I'd categorize Fly By Day as a summer song, but... as the weather warms up and summer approaches, you can't help but imagine what summer is like. I feel like Fly By Day does exactly that. It plants the seeds of summer in your mind, and makes you feel fluorescent.