I don't like to leave ammo in a car/truck for long periods as down here in Florida things can get hot in a hurry. I would say that as long as it's not in direct sun light it would be safe. I think moisture and humidity is the biggest problem with ammo. I keep mine in the house.

Thanks baldy. I was just worried about leaving it in the car for like a day or so when I go to the range.

I always keep an extra box of 9MM and .40 ammo in my truck. Living in Arizona I know it gets hot (but it's a dry heat). It has never failed to go boom after residing in the truck for a while.

I had an accumulation of old ammo, 12 guage, .308 and .22 which I carried from Arizona to Alaska to Texas back to Arizona back to Texas and finaly back to Arizona over a 35 year time span. When I decided to test it, all worked as expected.

The .308 was Winchester 180 gr. silvertip and shot the same as a fresh box at 200 yds.

Good ammo is tuff stuff

Enjoy.