Witchipedia

Deja vu is a normal psychological "trick" of the mind involving memory function. The mind wrongly believes it is experiencing recall instead of experiencing things for the first time. This is perfectly normal. Prolonged deja vu or other factors such as hallucinations could point to an illness or cognitive difficulty, so if you're worried about it, seek medical advice. If, however, you have dreams or experiences well in advance of something actually happening in real life, then you may be experiencing precognition. There is no scientific explanation for this, indeed it goes against the laws of physics, but just because it can't yet be explained doesn't mean that it doesn't happen. Science explains and rationalises this by suggesting that 1) we may be experiencing selectional bias 2) we are picking up subconscious cues that we are otherwise unaware of and 3) the event is a self-fulfilling prophecy brought about by us having thought about it in the first place. A fourth explanation-my own - is that of probability. Of all the things you might think or dream at a certain point, statistically one of those things is coincidentally likely to happen in real life. As a realist I take all of these things into account. However, as a witch I am also open to the idea of interconnectivity and collective consciousness, and also that time does not necessarily always travel in a straight line. I keep an open mind and, having experienced significant precogniton on two occasions, I tend to take notice of random "signs" that come to mind and note them to see if they have meaning later on. If you are worried that your predictions signal some sort of danger, then by all means warn your loved ones to avoid blue lorries/ red cars/ bonfires or whatever signals some sort of unease, but otherwise just enjoy it. If it's persistent and prolonged and it worries you, seek medical help.