Is there a highway or landmark that is used to separate the north hills from the south hills?

Thanks...trying to figure all of this out.

PM me if you'd like

Not really, there isn't a boundary that is really recognized universally. typically when I think of the Northern hills it means anything north of Rapid city, and southern hills would be anything south of custer/hill city maybe.
are you looking to find a particular place? I'm pretty familiar with the area

Are you talking from the point of view of the deer regulations?

Just in general. Not from a deer regs stand point.

Colorado, sent you a message.

You can see the actual change from the north to south land forms in Custer State Park. Drive the Wildlife Loop. The northern termini are in the northern land forms, while the southern "bottom" of the loop is in the southern landform. It is a fairly distinct change.

What's the average weather usually like in mid November?

November weather here is...variable. Historic weather data is available on line. The weather on any day may vary significantly across the hills, our storms in general are small and one can move from the north to the south to avoid the majority of bad weather. Probably goes without being said but the mid November weather varies between T-shirt pleasant to down right nasty. The Atlas storm in 2013 dropped 4 feet of wet snow at my home, Lead received 55" October 3-5.

It can vary from 70's and t-shirt weather to blizzards and negative temps. I have hunted in both during November.
Some years, you carry extra water in case of fires, some years there is feet of snow blocking hunting access.

So you can Google average temperatures, but in reality, it is a month of extremes.

aint that the truth! last year it was 60 when my wife killed her buck nov 13. fast forward 5 days and it was 10 degrees when I shot mine and 6" of snow on the ground.