Abstract Objectives For a long time, science has searched for the relationship between weather and human health. Atmospheric pressure is the most objective weather factor because, regardless of whether the objects are outdoors or indoors, it affects all objects in the same way. In cardiology, we often look for factors that worsen blood pressure control. Could atmospheric pressure be one of them? The main objective of our research was to assess the relationship between atmospheric pressure and blood pressure in patients with treated hypertension in different months in the moderate climate of Central Poland. Material and methods The study group consisted of 4191 patients with arterial hypertension, divided into 2 near equal groups due to a lower or higher average value of atmospheric pressure when blood pressure was recorded. Blood pressure was monitored by a means of 24-h ABPM. Atmospheric pressure was recorded with the frequency of 1 measurement per minute using a meteorological station. The observations were conducted in the years 2009–2019. Comparisons between blood pressure values in the 2 groups were performed using the Mann-Whitney U test. Results We observed a significant difference in blood pressure recorded during the periods of lower and higher atmospheric pressure: for systolic blood pressure during the days of September (125.01±14.99 vs 120.14±12.83, p<0.001) and December (124.22±15.45 vs 127.50±14.35, p<0.05), for diastolic pressure during the days of March (72.24±10.92 vs 69.81±9.13, p<0.02) and for diastolic pressure during the nights of March (61.53±8.96 vs 59.58±9.17, p<0.04). Conclusions A significant inverse relationship between atmospheric pressure and blood pressure was observed; during March days and nights for diastolic blood pressure and during September and December days for systolic blood pressure. This finding may be important for the understanding of why during some months the pharmacological control of blood pressure is poor, and of the consequences of this fact. Funding Acknowledgement Type of funding sources: Public hospital(s). Main funding source(s): own resources