How Shelters Work
There are several benefits to a shelter:
- You don't need a fire to sleep
- Most shelters have beds which are better to sleep in than a bedroll
- Some shelters have indoor fireplaces so you don't have to go outside to cook or melt water
- Most contain storage containers for your stuff
- Protection from predators
Shelters (usually buildings) are much warmer than the outside temperature. This makes them safe to sleep in without a fire as long as you have some decent clothing. You can use a bedroll or a bed if there's one inside.
Most shelters trigger a loading screen when you enter. If you see a loading screen then you know you're in a safe place. A few shelters do not load a new interior, but they still have doors on them. If in doubt, check your "Feels Like" temperature when you're inside versus when you're outside. You cannot build fires in a shelter except in a fireplace if it has one.
Shallow caves are typically warmer inside as well (make sure you go in deep enough). And you can build fires inside them. But they cannot be relied on like shelters. Again, check the temperature.
There are some large, explorable caves whose interiors load just like a normal shelter. These caves operate like shelters and are warm enough to sleep in, but you can also build fires in them.