Snowy biomes (Specifically areas where rain becomes snow) have a new temperature mechanic. Various factors, including the weather, time of day, blocks you're standing on, proximity to heat sources, blocks sheltering you from the sky, and more play into how cold you get. If you're cold, you'll slowly freeze to death. Get too cold, and it won't be slow anymore!
NEW WEATHER: BLIZZARDS!
Thunderstorms in snowy biomes have been replaced by a deadly snowstorm, sure to claim the lives of those who aren't prepared with proper shelter and warmth.
ATMOSPHERIC SOUNDS!
You'll hear some gentle wind when its snowing, which will turn into a howl during a blizzard, letting you know it's cold outside! The wind will cease when you are safe. So atmospheric, so realistic, wow!
NEW FUR ARMOR!
Leather armor can partially insulate the player from frigid temperature, but when comes a Blizzard, you'll need more to keep warm. Using White Wool, which can now also drop from Polar Bears and Goats, Leather armor can be upgraded to be more insulating, to keep you comfy in the most harsh of conditions...
...well except for being in water. Try to avoid that if you can, there isn't much to save you when you're submerged in freezing water.
VISUAL INDICATOR:
A visual indicator is enabled by default, but can be toggled in a dialog menu. The indicator shows the player when they are not warm and will slowly take freezing damage, and when they are cold and will take freezing damage faster