BACKGROUND: Hypertension (HT) affects >1/3 of adult populations in developed countries. Several studies reported periodic changes in blood pressure (BP) values depending on atmospheric conditions, and analyzed the impact of outdoor temperature, atmospheric pressure, relative humidity and other meteorological parameters. The Universal Thermal Climate Index (UTCI) is a bio-meteorological index derived from an analysis of human thermal balance that comprehensively describes the impact of meteorological factors, including both cold stress and heat stress and their physiological consequences. AIM: Our aim was to assess the relationship between UTCI values and the number of consultations for HT within the framework of the healthcare system. METHODS: This work presents a retrospective epidemiological study of data collected in Olsztyn (Poland), characterized by cold climate type. The analytical material comprised 5578 consultations in emergency departments (EDs) due to HT. RESULTS: Seasonal differences in the numbers of HT consultations with a significant increase in winter months were noticed, especially as regards women. Under cold stress conditions, the relative risk (RR) related to consultations for HT was 2-fold higher for women as compared to thermoneutral conditions (p<0.001). For men these differences were also statistically significant, though at a much smaller level (p=0.03). The increased RR of HT due to cold stress was found among younger and older women contrary to the women at the perimenopausal age. CONCLUSIONS: Cold stress should be considered as a significant risk factor among patients, particularly women, diagnosed with cardiovascular diseases. The UTCI is an adequate bio-meteorological tool for the assessment of relationships between atmospheric conditions and occurrence of cardiac symptoms.