So how do you think Absol predict natural calamities anyway? I always thought the horn on its head was covered with extremely sensitive, very short hairs. Like an Espeon's fur, the horn senses the air surrounding it, "feeling" the air to a degree we can't conceive. An Absol's horn isn't so much a horn, as much as a radarlike mechanism.
The subtlest changes in the air and even in the earth, it can feel, and that's how it knows in advance when something big is coming. It can forecast the weather and even walk around with its eyes closed because it can feel air bouncing off nearby objects, sort of like echolocation. It doesn't need to turn around to know you're standing behind it. Even if it couldn't feel your body, it would feel the air passing through your lungs.
But the downside of this, (or so my headcanon states,) is that its horn is far TOO sensitive, to the point where it would incapacitate Absol with pain if you so much as gripped the horn tightly. It's filled with blood inside, and would start to bleed and bruise if you so much as squeezed it a few seconds.
This is also partially why they go off alone in the mountains. They don't want to be around bustling environments, they're too sensitive and it's overwhelming.
