Surely every plant grows outdoors somewhere - that is, where they grow in nature. So how could a plant grow outdoors and not get rained on sometimes? These absolutely are not desert orchids (if there is such a thing).
My orchids all grow outdoors year 'round unless we get some really cold nights in winter. They get rained on randomly and get various amounts of sun. While I've now lost a couple of Zygo's in my outdoor growing conditions they both died during the dry season and did not mind getting wet with rain.. a couple of weeks ago we got 9in. of rain in 3 days. So yes, they get a real thorough bath at times. Be sure to keep your common sense hat on, and think of this as just a plant, first of all.
