UnReal World should have periods of severe weather to make winter properly dangerous and scary.
Blizzards with their high winds would make freezing temperatures much worse and turn layers of clothes into more of a necessity. Right now a person can easily go through winter without worrying about the temperature much. Cabins aren't that necessary for warmth.
Mechanically a blizzard would be a period where for 10 hours, or much more the snow animation is constantly on. With some random tiles in your view sometimes completely going white for a single turn. Visibility is reduced on the local map and global map. Temperatures drop severely and should go lower than whatever the minimum is now. The interior of a building and cave should provide the most protection. Shelters made up of conifer branches can still help, but you should require a large fire going constantly on the tile beside you. Frostbite on your hands, face, and feet would be a big hazard during the storm.
Weatherlore will need to be updated for blizzards. Based on your skill, you will be able to detect if one is coming in the next day. Or couple of days. As you become more skilled, you can guess more details about it, like how herblore works.
Like at 10% skill you can guess if you're on the edge of a blizzard or not. Maybe how long it will last once you're in it, with A LOT of room for error. At 30% you might be able to see a blizzard a day ahead. And so on. Perhaps it's not very realistic to accurately predict a snowstorm in the dark ages, but it would make the weatherlore skill more interesting and valued.
I think it would be interesting to put all the features of a blizzard on some kind of Bell Curve using multiple dice. Making snowstorms with "mild" values the average and expected. But once in awhile you may roll very brief storms or very long ones that last a week. Some may have worse visibility and temperature, or not. This way not all blizzards will be the same and it will allow for more memorable moments where characters can become lost and stranded in severe weather. Certain months during winter should be at more risk for blizzards as well. Like the "Winter" month(December) and most others during the season may have a 4% chance per day of developing a blizzard. Center month(January) may have a 7% chance each day. I don't know Finland's weather cycles very well, so I don't know which parts of the year is most at risk for bad weather. This is just an example for weather chance.
This would open up the way for more quests too. Like a questgiver in a village might ask you to go rescue a family member that was returning from a hunt or their traps. The quest could be open during the storm or afterwards for awhile.