Sometimes when its maybe 25 or so overnight, I get in the car in the morning and the radio has no sound. It appears to be working but no sound.
Didn't have a CD in so don't know about that.

Possibly the amp?

Has always started working again. Today, not until this afternoon when I drove home.

Had this happen a few times over the past two or three winters. Anybody else?

Cheers

Battery? My Cayenne radio had intermittent issues. Finally the battery died and the issues disappeared after replacement.

OP, I've been experiencing a very similar issue with my radio but it has nothing to do with lower temps (in my case).

The PCM unit is on, I can select different radio stations, menus, etc. but no sound comes out of the speakers. Then it suddenly bursts into life by itself. Sometimes it works perfectly for days and then the problem might resurface multiple times in one day.

I took it to the dealer and they determined that it was the amp. I'm currently waiting for a new amp to arrive from Germany in a couple of weeks.

I replaced my battery a few months ago so at least in my case is definitely not related to having an old battery.

EDIT: Forgot to mention that once the sound comes back, it stays on. Only case when it goes away is when the car has been shut off.

The dealer already tried resetting the PCM, and it seemed to have worked for the first week or so, but then the problem came back.

Could be amp related as another poster reports.

My 996 Turbo has manifested something similar off and on. Get in the car and start the engine then when under way turn on the radio and it comes on, all the controls work -- channel selection buttons, etc. -- but there is no sound.

Turning the unit off and on has no effect.

Talked to tech about this and he said I can pull the radio fuse to cause a power reset or shut off the engine for a while. Puling a fuse is too much effort and I know from my work the Turbo takes approx. 3 minutes to fully power down after turning off the key and I don't want to wait that long. So I drive in silence.

But the next time I start the engine the radio is working again.

What I have found is the behavior is not limited to cold weather but appears to be a precursor to a bad battery. In writing this post I was thinking about this behavior and I can't recall having this behavior appear in a long time and the battery in the Turbo is relatively new, probably no more than a year old.

dont know what car you have. my 09 was doing something like that, no sound on xm, and dealer did a update download and t fixed it . I dont think any temp will affect it

2005 997.1
Recently replaced the battery, so I don't think its that, although its predecessor did crap out rather dramatically a some months early.
I will post if it happens again.
Thanks.