Hi @JenE 

Welcome to the Sonos Community!

We don’t manufacture a Sub that can go outside, so we can’t really recommend that you use one of ours. As the Sonos Amp has a port for 3rd-party, powered Subs, if you can find one that will bear the weather I’m sure it will work. I cannot recommend one however, but perhaps someone in the community has done this before. Any 3rd-party sub would need to physically connect to the Amp, which itself will need to stay indoors.

I’ve done a little bit of research on outdoor subs, and it seems they are typically not powered.  They will connect via speaker wire, the way any other outdoor speaker would, just with the right crossovers to limit to bass frequencies.   That makes sense, but it also creates a bit of a challenge for powering a pair of speeakers and sub off the same amp.  Also, it seems that many outdoor subs are designed to be paired with their own speakers.

Here’s an example of one.

https://www.crutchfield.com/p_107ASB100G/Polk-Audio-Atrium-Sub100-Gray.html?tp=188

Notice as well that it goes down to 50 Hz.  Indoor subs almost always get lower than that.  You can get a pair of Polk Atrium 6’s that also go down to 50Hz for the same price.  I’m sure there’s other differences...but is it worth it?  Many people also feel that subs just aren’t going to have that great of an effect outdoors regardless.