The Sonos One is safe to use in a bathroom and it is far less water resistant than the Move. So I would imagine the Move would be safe even in a high humidity bathroom as long as it is not submerged in water. I’m not sure about the charging base though.

I know the charging base is not, but I can’t find anything definitive about extreme humidity. 

freestyler0890,
 

The Sonos Move is IP56 rated:

An IP rating is an international standard that defines how effectively electrical enclosures resist intrusion from foreign elements, such as dust and liquids. The numbers that follow “IP” have specific meanings. The first ranges from 1-7 and defines the degree of protection from foreign elements, such as dust. The second ranges from 1-9 and defines the degree of protection from various forms of liquids, including sprays, drips, and submersion.

Move is rated IP56, meaning it is protected from very fine particles, such as dust, and heavy liquid splashing, including heavy rain and snowfall.