The Forecaster is an orphaned child living under a bridge at 188 Trading Post. He earns caps by selling thoughts to curious travelers passing through. The Forecaster calls the process by which he comes up with his thoughts "thinking" because he is unsure of the origin of his thoughts and is unsure whether he derives his thoughts from a supernatural ability or a very perceptive mind that can digest and make sense of the chatter and movements he sees at the 188. The origins of his thoughts appear to be the massive migraine headaches that he suffers from, which cause his strange and perceptive thoughts to come out. He wears a psychic nullifier which he calls his "medicine". The medicine he claims keeps him from thinking about much during the day, causing his thoughts to get bottled up and rush out as soon as it is taken off. Taking his headgear off to think causes him great distress and pain so the amount of "thinking" that he can do for one day is limited.
You can offer to buy his headgear but he will refuse. You can pay him 100 caps to "hear his thoughts" on "You", "Here", or "Everywhere". He is basically a fortune teller. If the courier questions him about his odd and disjointed collection of pre-War junk he will explain that it's not junk at all but other peoples' thoughts because people had to think to make them.
Bull and Bear over the Dam, at each other's throats... but a light from Vegas? Ball spinning on the wheel, morethantwoat the table. Placing bets. All lose in different ways. A dam of corpses, towns of corpses, scattered across the sand. But whose in what shares? Even the dealer doesn't know. Forecast: A rain of blood will flood the desert and not purify it.
On the PC Patch 1, the Forecaster can be seen floating in mid-air a few inches off the ground instead of on the ground in his sitting pose.
If the player has the Mister Sandman perk, visits the Forecaster at night and tries to pickpocket him while he sleeps, he will get the Murder option. However, The Forecaster is a kid and cannot die, but the player still gets the bonus XP. This way you can get unlimited XP points.
If you try to murder The Forecaster with the Mister Sandman perk, your player will just perform the falling asleep animation before immediately returning to crouching, without killing The Forecaster, although the player will still gain XP. If the player tries to murder The Forecaster again without fully returning to crouch, they may teleport into the rock face West of the crater where Moe is found.