Everything here is alterable and certian features are optinal in what I am proposing. I am just putting it out there for disscussion and constructive criticism.

The gods laid sheets across the lands
Basically during winter crops will not grow and animal spawns would be decreased slightly. Some forgeable will not spawn during winter they will be replaced with winter only forgables. Winter should come after 3 weeks of regular weather and last for a week. This would promote food storage, and will add many new strategic elements to the game world. It would be nice to see the land look difference once a month to give the game a fresh feel to it. Just as the coming of winter gives the game a fresh feel so will the end of winter make the old look feel fresh again. Also there would be winter only resources that would come up, it would be a good time to get those before they are gone!
Here are the some new forgables and their proposed replacement during winter (feel free add some):
Blue Berries - Winterberry
Dandelion - Sarcodes
Glimmermoss - Frosty Moss
Edelweiß - Snow Flake
Frog's Crown - Ice Crown
Chiming Bluebell - Icy Bluebell
Four-Leaf Clover - Calendula
Be Prepared!

Rob, what is that cracking sound?
An optional feature of winter would be water freezing. I would suggest a square of water to have a 1/20 chance of freezing on the new season change. It would require a tool to break the ice to return it to liquid form.There would be a new boat that could break through ice, just a regular boat with steel attached to the front, but the boat will lose durability as it breaks through ice and would need steel to repair. There could be a bronze and wrought iron version of the boat but it should lose durability faster than the steel. Water that has turned into ice would allow players to walk over them but with a 1/100 chance of it breaking under their feet. Putting them in the water to swim out if they can swim. If they player can't swim there would be a skill to take another player out of the water if the player is standing 1 tile away from the other player. There would appear a menu for the other player to accept the request. If the player uses the skill on an ice tile there is a 1/20 chance that the ice under him would break and cause a circle form of ice shattered around him. The circle shatter could also be applied to the person walking over it but at a 25 out of 100 chance of causing a circle fracture rather than a small crack. Icy water will drain your stamina more than regular water.

New NPCs
It would be nice if the these where changed for the season. New FEP and foods for this season only, so it's hunting time!
Bear - Polar Bear
Bones/Teeth/ White Bear Hide
Boar - Wolf
Bones/Teeth/Wolf Hide
Rabbit - White Rabbit
Bone/White Rabbit Fur /Curio: Very Lucky Rabbit Foot
Why am I shivering?
This one is controversial, here would be the clothing level and side effects:
I like to run around nude and punch wabbits:
Starving HHP damage effect, along with no stamina regeneration OR very slight regeneration. Food doesn't fill you up as much along with heavly reduced FEP bonus.
I was born again fresh into this world. (Basic noobie wear):
Reduced stamina regeneration, stamina drains more than normal when you run.
Wearing a fur coat:
All is normal.

I searched the ends of the world for these fine pieces of furs
Polar Bear Coat
1 White Bear Hide / 6 String / 4 Teeth / White Bear Meat
Wolf Coat
3 Wolf Pelts / 6 String / 4 Teeth / Wolf Meat
White Rabbit Coat
15 White Rabbit Hides / 6 String / White Rabbit Meat
The warmth of the flames
There would be a buff ''The warmth of the flames''. Any flame (Including Heathfires) or heat producing object will give that effect the longer you are next to it. Once you leave if the bar is full you will keep the effect for 10min or so. Here is the effects (Please note this buff is only available during winter):
Full exposed character:
Stamina regenerates, and there is no HHP damage.
Normal:
Normalized
Fur coat:
Gives a different buff: ''Prepared for the blizzard.'' Increases happiness.

The Ice Age
Every 3 weeks there is a chance an ice age will come about. An ice age will basically be winter extended to last 2-3 weeks. It would be very interesting to watch congress assembled during this time.

Feel free to criticize and add on more features to the winter time. It would be nice if this really came to existence.