Why do finger joints swell up in winters?

The finger joints swell up in winters because the cold weather causes the blood vessels in your hands and feet to constrict, which reduces the blood flow to those areas. When there's reduced blood flow, the cells in those areas don't get as much oxygen and nutrients, which can cause the cells to swell up.

Another possible explanation is that people tend to spend more time indoors during the winter months, which can increase their exposure to dry air. Dry air can also cause the cells in your hands and feet to swell up.