Aberdeen Proving Grounds did a study of temperature change on the velocity of .308 military rounds.
They claimed that there was 1.7 fps change in velocity per degree F.
I think that was for a IMR4064-like powder but, just like factory ammo manufacturers, the powder they use comes in very large lots that may be slightly different than what we can buy off the shelf.

I did some checking through QuickLOAD software for powders that I regularly use and found that their data for IMR4064 would come very close to that number for a .308.
Other powders varied from around 1.1 to 1.6 fps per degree F.

The change in velocity as temperatures drop will cause a change in point of impact not only down but I find it also creates slight change in windage because the bullet stay in the rifling slightly longer (maybe up to 0.02 msec. out of 1.256 msec. for a 24 inch barrel) and it apparently changes the spin rate slightly.