lol, yesterday i was siting in the stand with my friends, and it started to pour, i laughed and said 'rain stop, this is my rain dance' and i waved my hand back and forth a few times. i was goofing around, and my friends got a laugh. but it immediately stopped. it was just a passing clouds, so i have amazing timing, but if i actually did that, that's neat and freaky at the same time because i really wasn't casting, just joking.
if weather spells work or not, i don't know, i've never seriously cast one. personally, i wouldn't cast weather spells, you're playing God at that point, and you don't want to cause a flood or drought or something?
by 'Naturally Magical' you mean is your friend born with abilities? maybe, some people are. your friend should be careful then, you don't want things to backfire in his face. if you mean 'natural magic' i don't know if screwing with the weather would be natural, look into herbs and stuff, work with nature instead of control it.