Cold Marshes: This vast swamp, even more vast than the one called the Vast Swamp, just happens to be in the cold north, separating the boggy land of Blackmoor from well, everything else. This place is naturally known for the dangerous mists within and if stories are true, lost treasures. What's fun about the Cold Marshes is the denizens here: ice toads, ice trolls, hyena-men, bear-men, and the best, Frost-Men. These humanoids resemble regular humans, except they have icy skin and their left eye shoots a cone of frost. Now that's what I call an icy glare!
This vast sea to the north of the Flanaess is normally frozen except during the late summer months. It has everything a seafaring barbarian could want; seals eating fish, walruses eating seals, whales eating walruses and a leviathan lord eating the whales! Watch those titanic floating islands of ice, they are hard to spot in the fog. Side thought, does the Land of Black Ice produce black icebergs?
Land of Black Ice: Speaking of which, there is no region more hostile to visit than this place. Okay, maybe the Sea of Dust. Alright, maybe the Sea of Dust and Rift Canyon. Okay alright, Sea of Dust, Rift Canyon or the Vast Swamp. At any rate, the Land of Black Ice is a glacial expanse of unknown origin and explanation. Dangerous arctic monsters lurk here including the ubiquitous blue bugbear. This is a land of natural hazards and also a land of mysteries. There is a warm hidden valley, a City of the Gods and even ancient ice-buried automatons (see Raiders of the Black Ice in Dungeon #115). DMs, there is plenty of room to create stuff here if you can talk your players into braving the black ice.
Cold Run: This chilly tributary is found in the northern Flanaess (of course) starting somewhere south of the Wastes and cutting through the ominous Fellreev forest where it eventually meets up with the much bigger and more traveled Artonsamay River. What is there to say about this waterway? No really, I'm asking, because I've never used the Cold Run in my games. Never mind, found it. According to the Living Greyhawk Gazetteer, the Cold Run has eels and pike. I'm willing to bet where dangerous fish are found, there is also giant eels and giant pike. And where there is giant fish I'd wager there is giant fishermen too! That's the best I got.
Wintershiven: The capital of the Theocracy of the Pale. This city of 39,000 isn't particularly a nice place to live. It is said winters in the Pale are harsh and unforgiving like its people. Locals say there is two "seasons" here, the unbearable winter and the barely bearable "summer". Interestingly this city was burnt to the ground once and rebuilt again before the Pale eventually earned independence to be religiously oppressive. What else is there to say about Wintershiven? Well it's run by the bureaucratic church of Pholtus. Because of this, there is really no reason to travel to Wintershiven, unless you are a zealot as well. DMs you will have to crafty to talk heroes into coming here, preferably in the summer.
Coldwood: Not far from Wintershiven to the south, is an area within the Adri Forest called Coldwood. This place used to be the ancient elven City of Summer Stars before its prince, Darnakurian went mad and slaughtered everything with a magic sword called Hunger. Now a cursed chill hangs over the remains of this forest ruin and stoic elven guardians remain in place to prevent anyone from entering or leaving. If that isn't tempting to your players I don't know what is! DMs you can read more about the Coldwood and Hunger in the unpublished Ivid the Undying, free to download on the interwebs. Enjoy!
Hanging Glacier of Alisedran: Probably the strangest of the cold places on the list, the Hanging Glacier can be found in From the Ashes. It tells a tale of an explorer named Alisedran who was deep in barbarian territory for some reason within the Corusk Mountains (ahem, hex J-16 to be exact). What the mad man described was a glacier that drops off a cliff and shatters into a sheet of ice shards, falling down in slow motion like a massive "feather fall" spell was cast on it. The ice shards has many strange properties according to the story, evidently ranging from alchemy to summoning and breathing underwater. Whatever the case, this glacial area is definitely not a smart place for adventurers to locate, unless their goal is fighting ice monsters then it's an XP gold mine.
Snow, Ice, Frost Barbarians: The Thillonrian peninsula is home to three ancient Suel tribes that migrated here a millennia ago. Known in the common tongue as snow, frost and ice, they are respectively called Schnai, Fruzti and Cruski in the barbarian dialect called the Cold Tongue. I won't go into much more detail, they are a viking-esque culture who can be encountered in most of the "cold" locations covered in this post.
Icespire: Here's a creepy cold location that I recently covered. Icespire is in the South Province (Ahlissa) and is one of those places that you think of in movies or cartoons when an icy curse befalls the land. Read it for yourself, but trust me, this isn't the safest place to go on the "cold theme" list, including the Land of Black Ice. Here we go again...
Icehand Plain: Last but not least. First featured in the excellent book, Iuz the Evil, this place is usually just an empty camp off the Road of Skulls 364 days of the year. It's true importance is that on the last day of Sunsebb each year, Iuz holds a massive pep rally for all his chiefs, warlords and high priests. During this rally, Iuz manifests a giant floating hand of black ice that points to each leader as he judges their loyalty. If they displease the Old One, then they are blasted into dust! In my opinion, this is all a ruse to scare his evil henchmen. Maybe one hapless creature gets killed to make an example, but I bet it's all predetermined. He is the god of deceit after all. At any rate, real of not, the Icehand Plain rally is a devilish place to have players stumble upon if the DM wants them to realllllly be intimidated, or if the players want to wipe out the entire core of the Empire of Iuz in one fell swoop. Whichever. Good luck heroes!