I don't think the outside temp has too much to change. However if you are sighting in your rifle and not allow enough time for the barrel to cool then you would probably have a change. My BC is dead on a cool barrel, but once it warms up it climbs about an 1 and either a 1 to the right or left. Now in all honesty your still in the kill zone but it does effect the bullet. I think as long as you sight your gun to a clean cold barrel as would your first shot be. You wont have any problems with outside temps.

No matter if it's Hot, Warm or Cold you should Always check your POI, it would if anything give you a Pice of Mind to know for sure where your at. I dont care if I sighted in when whatever Temp it was, befor I go Hunting Im checking to make 100% Sure Im where I shoud be.
But I have also Hunted on some Pretty COLD Days and I still hit where I was aiming, and I know for a fact that I did'nt sight in when it was Below Zero out. So with that said it would be Impossible to know exactly for sure where your gonna hit when the Temps vary so much, just check it befor your Hunt and that's all you can do.

if your talking about a clean barrel here that could be your issue.

Never had any impact changes from a so called warm barrel....