ABSTRACT
<p><b>OBJECTIVE</b>Seasonal variation in blood pressure had been observed in several studies on Western populations, but uncertainty remains about the strength of the relationship in other populations and the extent to which it was modified by other factors.</p><p><b>METHODS</b>This study was based on cross-sectional data from the China Kadoorie Biobank study with 53 260 men and women from the Suzhou area involved. Linear regression model was used to analyze the association of blood pressure with outdoor temperature-overall and in various subgroups.</p><p><b>RESULTS</b>Blood pressure varied with the seasons, ascending in winter and descending in summer. The difference in systolic blood pressure (SBP) between summer and winter was 8.8 mm Hg in men and 7.0 mm Hg in women. SBP was inversely correlated with outdoor temperature, especially above 10°C, with every 10°C colder temperature causing 6.1 mm Hg increase of SBP. The seasonal variation in SBP was more obviously seen in older people and in those with lower body mass index.</p><p><b>CONCLUSION</b>Blood pressure was strongly and inversely associated with outdoor temperature in the population in Suzhou area. Seasonal variation of blood pressure should be considered when the hypertension screening programs, clinical management and data management on hypertensive patients.</p>