I've found that the experience of Etiäinen is quite common amongst those people I've spoken to who are not into paranormal or high strangeness events.
In Finnish Folklore, everything has a Haltija. everything being all places, items and people. Haltija has the meaning of Guardian Spirit/Genie.One type of Haltija is an Etiäinen, which means an image, doppelgänger, premonition (positive or negative) or just a knowing of what someone will do in the very near future; as in you hearing/seeing things that that person will actually do later, like an impression.
Imagine you are at home alone. You hear the keys going in the door and it opening, followed by footsteps, maybe even a shadow. So you go towards the front door to welcome that member of the household but only to find there is no one there. 10 minutes later, that member of your household does comes back and you hear the same noises and images from when that you did just 10 minutes beforehand.These moments are called etiäiset when you've experienced them several times. They can even cause you to feel anxious and ungrounded. They are usually small events but there have been incidents of more serious events such as injuries or death.
Experiencing this type of event can sharpen your other senses, such as sight or hearing so that if you are waiting to see someone, it can bring an image of that person and your mind can project that thought. This is one explanation and could possibly answer some or part of these events but not all.
Etiäinen has deep roots within Shamanistic origins and was said to have been a spirit sent to a person in distress by a Shaman.