Rain!
I find it very entrancing.
When the sky is light blue, with splotches of different shades (while raining).
When it's sunny (while raining) and all the colors seem to merge kind of.
I was lucky enough to have one of my xC meets when it was sunny and raining and it was awesome, refreshing, and the air feels so much cleaner.
Rain washes all paint marks away, and aids in growth of plants.
Yeah rain is my favorite weather of all.