Sore knees in summer may be caused by osteoarthritis, rheumatoid immune system diseases, and previous joint injuries. 1. Osteoarthritis: in summer, although the outside temperature is relatively high, but people are often in the air cooler places can cause blood circulation to slow down. In addition to this knee joint inflammation can lead to localized oozing, edema stimulation of peripheral nerve endings, can cause knee pain. 2. Rheumatic immune system diseases: rheumatism, rheumatoid arthritis and other rheumatic diseases, summer in the air-conditioned room due to the cooler environment, the knee is easy to get cold, triggered by the knee joints, the patients appear knee pain. 3. Previous joint injuries: patients with previous knee trauma has not completely healed or the formation of traumatic arthritis, to the summer when patients can appear knee pain. There may be other reasons for knee pain in summer, so it is recommended to go to the hospital in time to improve the examination to clarify the cause of the disease, and then give targeted treatment or therapy.