Weather considerably influences cardiovascular health. It is a well-known phenomenon that cardiovascular morbidity and mortality increases during winter.1 This observation is attributed to multiple physiological changes that occur during winter, such as increased sympathetic activity,alteration in the coagulation profile, endothelial dysfunction, and increased blood pressure (BP).2,3 Of various weather parameters such as temperature, relative humidity, frost, and sunshine, outdoor temperature is the most important determinant of BP fluctuation and is inversely correlated with BP.4 Studies have shown that BP increases with decrease in temperature.4–۱۲ The climatic conditions in tropical areas are considerably different from those in temperate areas, with extremely hot summers and near zero temperatures during winters, resulting in an unusually large seasonal variation in temperature.In addition to geographical location,many other factors affect the strength of the association between temperature and BP in low–middle income countries such as India. A considerable proportion of the population consists of manual labourers and farmers who work in natural outdoor conditions. Housing conditions (lack of central heating) and other known risk factors of hypertension (obesity, age and social stress) are different as compared to western countries which can modify the effect of season on blood pressure.5 Despite being one of the most populous areas of the world, no adequately powered community-based study has been conducted in Asia in out-of-clinic settings, evaluating the effect of temperature variation on BP within same subjects in general population. Thus, we conducted a community-based longitudinal study involving subjects from both rural and urban areas. The aim of this study is to determine within-subject fluctuation in BP in out-of-clinic settings in native surroundings (either home or workplace) for evaluating the effect of change in season and outdoor temperature on BP. Recently, it was also reported that seasonal variations are more marked in rural areas.6 Since two third population of India resides in villages, the current analysis was done to see rural urban difference and other factors affecting seasonal variation in blood pressure.