Items too equip on you like the smoke mask and Biohazder mask will break overtime and will need to be fixed/replaced/found and they go in tiers that increase durability and protection
Weather in the pine forest for minor heat and cold. And storms for forest which are
Heat waves/cold fronts
Heavy rain (slows you down)
Snow/sleak (makes you very cold)
Super heat wave (makes you very hot)
Other biomes have different hazards rather then just heat/cold.
Desert has dust insulation
Snow has shortness of breath/tin air and harsh windchill
The undercloths for your arnor add a 1 point of protection and they are shown just over your character. If you wish too see it then you can use the wardrobe system it goes as
Basic hats
Outfits or even just pants and shirts
Socks
Wraps/cloths for gloves
Some even provide extra minor bonus like
Working socks increase stamina with tools by 5%
Athlete socks decrease stamina lost by 5%
Sports outfit increase stamina 5%
Sweat band descreses stamina with melee
Working shirt increase block damage
Casual business outfit increase bartering buying
Business shoes increase sell value
Bdu increase ranged damage by 5%
Lumberjack and mining shirt increase mining/harvesting of each respective item by 5%
A new slot for survival kits too help aid you. Crafted with materials set with the them abs even weapon/armor mods. These provide extra bonus too whatever your doing. These will appear on your person visually as well as a satchel with different badges, back backs, side mounted Charms, first aid or drink kits
Scraping/hunting/harvest kits
Light, small, mid, large, ultra light backpacks
Looting/bartering/quest Charms
Extra health/stamina kits
Etc
zombies
Old frostclaws and desert spitters are now mining bosses, slightly larger and more deadly
Mutated Zombies can now spit a volley of radioactive spit or emit a plus of Radation
Effects
Heat/cold/Radation/smoke insulation/dust has levels of exposer and give you debuffs the longer your in/suffering those effects
Biomes like the wasteland give you Radation sickness while you swim, snow basically insta freezes you
Wildlife
All biomes have hostile Wildlife. The forest having the most varried amount
At night deer come out the most but so does everything else