Car: 2012 chevy cruze ls, automatic. Has 58k miles on it, I got it a few years ago with 51k miles on it.
Symptom: Rattles on startup. ONLY does it when its over like 70 degrees, or especially if the interior is blazingly hot. DOES NOT do it when its cold or lukewarm, or under 70 degrees Fahrenheit. Goes away after a few seconds.
Is the noise coming from under the hood? If so it could be piston slap. (Oil is thinner when warm.) I'd also take a close look at the condition of the timing belt, tensioner, and water pump as well as serpentine belt and accessories driven by it.
If the noise is coming from under the dash there's probably something in the HVAC system rattling around when heat makes parts expand (actuators, flaps, or blower.)
If you can post a video with the noise it might help in identification, though frequently locating noises is a "hands on" operation.
Of course the next several days it may not do it because its going to be a bit colder. Il try to get some within a few days though.
I would suggest a recording of the sound. Pinpointing where it is coming from will help with diagnosis.
Within a few days I will, thgen I'l edit this comment. Again since its gonna be cooler for the next few days I'l get it when i can.