Mellow as in, listening to really chilled out music, with your bedroom window open, having your music and the rain falling become synced?
I find there is something relaxing about the rain, it has an effect on me that I didn't know rain could. Rain makes me feel peaceful, and calm. I remember when I was younger, and I would be at the lake with my parents I loved the rain and watching it fall on the lake, I still think its one of my favorite things to do.
I believe that the weather has a very large effect on the way I feel, and what mood I am in. If it's sunny I am usually energetic and up for anything, the rain, make me want to sit and watch it fall, preferably at the lake with my feet in the water getting soaked! Cloudy with no rain make me feel like a hermit, just staying inside and doing nothing but napping and watching movies.
While in my mood of peacefulness I found some great music, Joshua Radin happens to be the artist of all things good. I also like, Kate Voegele, Lisa Hannigan, and Emmy Rossum, but just for the rainy days!
Here is one of Joshua Radin's songs called Today, hope it makes your rainy day better!
What is your rain mood?