Stereo going Crazy

Rapture, you're going to have to start a process of isolating and testing.  There's no way a broad problem like this can be pinpointed in cyberspace.  Start with the speaker wiring or whatever component you wish, and isolate/disconnect from the system until you find the source of the problem.  Test all wiring for shorts with a meter as you go through.

For example, if you were going to isolate the speakers you would gain access to them and disconnect the factory wiring.  Then you'd connect with temporary new speaker wire directly to the amp (...and please don't ask how these might be the source of the problem.  You just have to eliminate everything that is acting up as the possible culprit.)

It's just a suggestion for a start if you want to tackle this yourself.  Depending on your skill level, it might take some time and result in a complete removal anyway.  But a skilled tech will have some procedures he would do first before removing anything, like testing the vehicle electrical system.

It's called thermal expansion and contraction.  Most likely cause is loose connection(s), corroded connection(s), or faulty equipment.  Hmm, didn't someone say that already?

your grounds should be a starting point. all of them. the vechiles grd under the hood , body grd, engine to chassis grd. obvisously you have a voltage drop somewhere from the percipitation of the weather and causing what ever has a bad connection to act up. if it's cold when it does it and still does it when the cabin of the car is warm, i would go under the hood first. but could still be in the car.

go for the grounds first. all of them even inside your car. then down the ladder of trail and error you go. if the grounds didn't solve it. good luck

keep it wired