Weather Insider: Weather-related joint pains
The weather can affect people in many ways. For some, their joints start to hurt when some unsettled weather moves in. This is because of low pressure. As the atmospheric pressure falls over a given area, it can cause the muscles, tendons, and other soft tissues to expand. This puts excess pressure on our joints, leading to discomfort for some.
The reason these pains are often associated with cool and/or damp weather is because that's the type of weather typically associated with areas of low pressure. Troughs tend to bring in cooler air from the north and often lead to rain.