Wild Arctic is completely indoors. Any "outdoor" portions are simulated like the interior of Pirates of the Caribbean or Mexico at Epcot. Don't let rain stop you from visiting this time because Wild Arctic is one of the best animal exhibits at the park (besides being a fun ride), and it's a great place to escape the rain. Although I suspect lots of other people will have the same idea, I'd rather be waiting in a crowd out of the rain to visit Wild Arctic if the alternative is leaving.