I wouldn't leave my gun anywhere I'm not unless it's at the gunsmiths or my safe.
The weather isn't a problem. It's thieves.
Don't do that -__- if you're not going to carry it then don't drag it along with you.
Only way I can see that being reasonable (leaving your gun in the car) is going into a courthouse or in the vicinity of a LE building. And then it should be in a lock box. Not the glove box. I don't care if it locks. Not good enough.
A real steel lock box.
Sáncte Míchael Archángele, defénde nos in proélio, cóntra nequítiam et insídias diáboli ésto præsídium. Ímperet ílli Déus, súpplices deprecámur: tuque, prínceps milítiæ cæléstis, Sátanam aliósque spíritus malígnos, qui ad perditiónem animárum pervagántur in múndo, divína virtúte, in inférnum detrúde. Ámen