It could be 70 degrees, it could be 40 degrees. Be prepared for both.
Course conditions- the golf courses in Hilton Head overseed with winter ryegrass or poa trivialis, and in January they are lush and green.
It probably isn't too crowded, even at Harbour Town. Heron Point, the newly remodeled course part of the Heritage package, is TREMENDOUS, but very difficult.
Harbour Town is outstanding, but be prepared to walk a bit, even with carts, because Harbour Town is cart path only year-round. The third course, the Ocean course, is very pleasant and not nearly as difficult as Heron Point.
This is a great package, no doubt. We were just there in October, and the staff at all the courses treat you very well, even though its quite busy that time of year. Have Fun!!!!