It's possible people are able use aches and pains to predict weather. Or they might just be imagining it.
We've all seen movies where the grizzled prospector, grizzled sea captain, or grizzled space marine lets out a pained sigh and says, "Yep, thar's a storm a'comin'." It could also be, "Weather's turnin'. Better get the young'ns to the far side o' the mount'ns," or "Nope, you new com'rs won't last through this'n here winter," or something else with an equivalent number of apostrophes. One can't be grizzled without speaking in apostrophes. Just look at Wolverine. The point is someone with enough bodily damage could feel a change in weather coming. How?
The key is pressure change. The weight of the air around us maintains a certain pressure on us at all times. Drops in the pressure, especially sudden drops, indicate bad weather. Higher pressure tends to mean sun. Pressure is measured using barometers. Most barometers are basically tubes of liquid with little sacks of extra liquid at the bottom. When atmospheric pressure increases, the sacks at the bottom are squeezed like a juice box, forcing more liquid up into the tube. When the pressure drops, the pools are let go, and the liquid falls back down. By looking at the level of the liquid in the marked tube, people are able to measure the current atmospheric pressure.
The human body doesn't have clearly marked tubes, suitable for viewing, but it has a whole lot of little sacks filled with goo ready to be squeezed. Some of the most common of those sacks, cited by grizzled people everywhere as the source of their predictions, are the joints. In between two bones is synovial fluid, which helps to make the motion of those bones as frictionless as possible. A drop in atmospheric pressure causes the tissue around it to bulge outward, the same way a balloon would if you put it in a vacuum.
Blood vessels are also liquid-bearing squish-sacks (It's a scientific term. (But don't google it. (Trust me.))) and when pressure drops enough they also bulge outwards. This causes pain for those prone to migraines. It also aggravates a condition called Raynaud's phenomenon, which causes spasms in blood vessels in the extremities.
Changes in pressure also greatly affect gas pockets in the body (Don't even make a joke.) such as the sinuses (There, now aren't you ashamed?). This also provokes headaches, or simply the sensation of pressure or stuffiness in the head.
These pockets, balloons and tubes aren't checkable from the outside the way barometers are, but fortunately we have a little bodily alert network called the nervous system. Nerves line the many sacks, tubes, bands, and joints in our body, always ready to come crashing into our brain with a little thing called pain to let us know something's wrong. This is the reason that the more apostrophe-prone among us can supposedly tell when the weather is changing. Not only are tissues less resilient as we age, but we are likely to have some condition, like arthritis or Reynaud's, which has already put our nerve network on high alert.
This high alert is the problem. In the movies, the prediction is most likely true. In real life, many doctors doubt that it is. A rainstorm that comes and goes without causing a twinge will be forgotten, but a rainstorm preceded by pain will be remembered. Some studies have been done which show that there is no connection between pain and the weather. On the other hand, a study done on rats with inflamed joints showed an increase in pain in low pressure, low temperature situations. Some doctors ask patients to keep a journal which details the amount of pain they're in and the weather conditions as a way to manage their pain, the question still remains. Are some people walking barometers? Or are they reading too much into a little pain?