Barometric pressure -- or the pressure of the air -- can affect joints, but humidity, precipitation, and temperature are also at play. That makes it tricky for scientists to pinpoint exactly what it is about the weather that leads some people to report more pain when it’s cold, rainy, or humid.

It’s common to blame joint pain flare-ups on changes in the weather, and many doctors believe people can feel more joint pain on cold, rainy days. But the research on the connection between the two isn’t clear.

Maybe your grandmother knew a storm was coming when her knees started to hurt. Or you’ve felt your own joints ache when the temperature outside drops.

How Weather May Affect Joints

Scientists have done many studies on joint pain and weather over the years, but so far, none can say for sure what the connection is. Part of the problem is the studies themselves -- many have used surveys of just a small number of people, which isn’t a very reliable way to measure a link.

Still, there are a few theories about the relationship. One is that people with joint pain, especially arthritis, may be sensitive to changes in barometric pressure. How? It could be that when the cartilage that cushions the bones inside a joint is worn away, nerves in the exposed bones might pick up on changes in pressure.

Another idea: Changes in barometric pressure may make your tendons, muscles, and any scar tissue expand and contract, and that can create pain in joints affected by arthritis. Low temperatures can also make the fluid inside joints thicker, so they feel stiffer.

You might also feel more pain when the weather keeps you from moving around as much as you typically do. People tend to stay indoors and lounge around more when it’s cold and rainy outside, and inactive joints can get stiff and painful.