Iron Wastes

From Fiendish Codex I: Hordes of the Abyss (3.5e):

The frigid Iron Wastes are home to the dullard lord Kostchtchie, the malformed demon-giant who claims all frost giants as his protected kin. A place of unrelenting blizzards and icy rifts, the inhospitable layer might have been  avoided by most Abyssal inhabitants if not for the presence of one of the most coveted gates in the Abyss, a rime-encrusted stone monolith arch leading to Jotunheim on Ysgard, near the frost giant town of Utgardt. More importantly, the gate opens near the roots of the Great Wheel-spanning Yggdrasil Tree, a major transplanar thoroughfare leading to locales throughout the Upper Planes. Demons from all corners of the Abyss therefore congregate in the Iron Wastes in hopes of moving through this gate, but Kostchtchie's fierce protection of his home realm results in de-facto protection of the Yggdrasil, making the Prince of Wrath one of the most hated demons in the Abyss, despised by good and evil alike.

The Prince of Wrath nonetheless enjoys strong support from his chosen people, tribes of frost giants from the Material Plane who have sworn themselves to Kostchtchie in return for eternal life in the Iron Wastes. Such is the demon lord's control over his Abyssal layer that he can prevent the aging and natural death of mortals who dwell upon it. While intended as a reward for the demon's chosen folk, several canny mortals benefit from the effect as long as they can avoid detection.

Weather in the Iron Wastes ranges from cold to extreme cold. A number of locales within the Iron Wastes bear further discussion.