In a one month prospective study of 62 rheumatic patients--16 with rheumatoid arthritis (RA), 24 with osteoarthritis (OA), 11 with inflammatory arthritis, 11 with fibromyalgia joint pain--swelling and everyday activity was compared with changes in daily weather conditions. In most patients weather changes increased arthritic symptoms. Women were more sensitive to weather than men (62% v 37%). Pain was affected positively by barometric pressure and temperature in RA, by temperature, rain, and barometric pressure in OA, and by barometric pressure in fibromyalgia. These results support the belief of most rheumatic patients that weather conditions significantly influence their day to day symptoms.