Weather will soon be integral to survival on JT2! Ambient temperature and the temperature of items being wielding can directly affect a player's sense of heat and cold. Thankfully, armor can be worn for protection such as chestplates, helmets, boots, and leggings which offer varying rates of conductivity and insulation depending on the material.
For example, steel boots would be horrible for walking through large banks of snow, since they have high conductivity, resulting in eventual frostbite of your feet. Likewise, cactus chestplates have high insulation, so wearing it while mining obsidian will lead to heat stroke since your body temperature rises as you do more intense work.
A player's sense of temperature is also affected by radiant nodes within close range, such as lava or fire. In addition, holding onto hot or cold conductive items for too long, like ice cubes or lava buckets, can burn or freeze you. Swimming in water for extended periods can also lead to hypothermia if the outdoor temperature is too low. And even after you resurface it will take a moment for your temperature to adapt to the surroundings until you shed all of the water from your body.
You can see in the screenshot above how my "felt_temp" decreases rapidly right after removing all of my armor since I am standing on a block of ice even though the ambient temperature is 72 degrees Fahrenheit. But a few seconds later, when I put my hefty cactus boots on, my 'felt_temp" slowly increases again. But of course, it still doesn't even approach 72 degrees, as no boots offer 100% insulation.
I've done a lot of fine-tuning of the algorithm to ensure it is challenging but still playable. And overall i'm really pleased with the realism and immersion. I definitely think weather-based survival adds a whole new dimension to gameplay in Minetest :)