Engine noisy when cold outside

[Silver 99 Camaro]

Unrelated to my other post, when it's really cold out, below 32*, my engine is really noisy. It sounds like a thrashy, nasty, old engine noise. It does it even after the engine warms up. When the outside temperature warms up, it sounds perfect again. What could this be? I can only guess an accessory like PS pump, alternator, or something like that. Any help is greatly appreciate becuase it sounds kinda nasty.