I absolutely love songs that use seasons and weather to set the scene or convey the mood of the song. Its a very effective technique, in my humble opinion, and I use this method a lot in my own song writing.
Since most of the songs use "rain" as the main type of weather, the mix ends up leaning quite a bit to the sad side of things, but there's some variation. I decided to pick these songs preferentially too, because I just can't make a mix of songs like "Walking on Sunshine."
I hope this mix will remind me of Oregon too, while I'm way out east staring out the window of the library... or at least remind me being stuck inside isn't always that bad.