Just my thoughts as a Sonos user...

I do not know the precise detail about the Sonos sub itself, but on Sonos.com, it briefly mentions that only the Sonos Outdoor speakers by Sonance models is rated for outdoor use and presumably that also applies, at least in part, to the Sonos 'Move' speaker too, otherwise it seems to be the case that the majority of Sonos devices are geared for indoor use. 

However, I’m fairly sure taking such devices outdoors for temporary use would be fine, if they are covered and kept dry, but my guess is that prolonged exposure to moisture is most probably not going to do the sub any good, in the medium to long term, I suspect.

Hi @wklemp 

As a direct answer to your post title Humidity Resistance of Sonos Sub?  My answer is NO. The Sub is not humidty resistant.

Sonos clearly states on thier site either in the speaker description or FAQ’s which speakers are Humidity Resistant and/or Weather Resistant. Click the Link:

https://www.sonos.com/en-us/products/wireless-speakers

Limted use as suggested by @Ken_Griffiths is probably OK. However, you’d have no recouse via Sonos if a component not intended for moist environments or outdoor use failed to perform. Even for those speakers listed as such there may be denied circumstances where the end-user exceeded the recommended conditions.

Fellow Houstonian here, and I have to agree with the above.  Ok for temporary use, but I would not leave it out there permanently.  And I don’t think it’s just the humidity that would be a problem, but the summer heat, even if it’s kept in the shade.

Wait till a squirrel drops a few nuts down the ports...

OK, against everyone’s better judgement, I decided to go for it!  I built a small stand out of acrylic (first photo below with sub on top) so that any water running across the patio floor won’t contact the sub.  It’s placed UNDER a glass table (second photo shows stand centered in the base of the table with the glass table top removed).  

The stand ensures the sub won’t rattle the table and positions it about 5 inches below the table top, so no rain can blow in on top of the sub.  Finally, I added a small heater (a closet dehumidifier) below the sub opening (white tube shown in second photo).  I believe that small 10w heater can create enough convection current to keep air flowing to avoid condensation build-up on/in the sub.  

Since it rarely gets above 100 degrees here, max temperature should not be a problem.  And, it’s a screened porch, so the squirrel threat is neutralized!  We will see.  Regardless, the sound quality is awesome.  I’ll report back after the summer to advise whether the sub survived!