Knee pain on rainy days is related to cold, for the following reasons: 1) the knee joint is usually bad, and when it is cold, the pain-causing and inflammatory substances are not metabolized, thus causing pain; 2) the microcirculation of the knee joint is bad, and after cold, the blood vessels are constricted and the muscles are tense, resulting in incomplete metabolism of pain-causing substances, thus causing knee pain to worsen. If the pain is not relieved, the pain should be further diagnosed and treated by a pain doctor at a regular hospital. In general, if you experience worsening pain on a rainy day, you need to take precautions first, i.e. keep warm during rainy days or take care to avoid walking outside on rainy days. If you experience increased knee pain, you can go to a regular hospital, especially to a pain department for further diagnosis and treatment.