Introduction: In routine clinical practice, many patients attribute their joint pain to the weather. Objective: To evaluate the effect of climatic conditions in patients with osteoarthritis. Methods: This study was performed in patients from the Instituto Poal de Reumatología in Barcelona and the data were analyzed by Bioibérica Farma. We performed a prospective, double-blind study that included 80 patients with osteoarthritis who were compared with 42 controls. Pain evaluation (Huskisson's Visual Analogue Scale) and functional capacity (Health Assessment Questionnaire) were determined daily for 1 month. The climatic variables studied were temperature, humidity, and atmospheric pressure. Results: Our data show that patients with osteoarthritis have greater joint pain when atmospheric pressure is lower, indicating that conditions of low atmospheric pressure exacerbate pain in these patients. Conclusion: Our results suggest that, in future, modulation of pharmacological and nonpharmacological therapy in some osteoarthritic patients according to weather forecasts may be feasible. This could avoid, as far as possible, the joint pain and functional disability associated with the disease, thus improving quality of life in these patients.