'Love and Happiness' by Al Green. If there is one song that transcends the seasons, from a balmy, unbearable summer day to be cozy inside while a blizzard descends outside, this song fits anywhere.
The XX, I find somewhat melancholy and I adore listening to it in autumn, as the days disappear faster and give in to the chill that summer could never bring. This is when I read the dark adventure books of Tolkein. This is my time to devour fiction.
Jagwar Ma was fantastic for summer, floating tunes on summer breezes. James Brown tells it how it is to summer, keep working, getting it done, doesn't matter how high the humidity is. You gotta keep going!