This study investigated the seasonal effect on blood pressure (BP) variability. Patients on stable antihypertensive drug treatment were assessed with office (OBP), home (HBP), and ambulatory BP (ABP) measurements in winter, next summer, and in next winter. Fifty-eight participants with full data for winter and summer were analyzed (mean age 65.2 ± 7.9 [SD], 64% males). OBP, HBP and ABP (24-h; daytime) were lower in summer than in winter (P < 0.01), whereas nighttime ABP was unchanged (p = NS). Standard deviation (SD), coefficient of variation (CV) and average real variability (ARV) for systolic OBP were higher in winter than summer (p < 0.01/ < 0.05/ < 0.01, respectively). These indices for HBP and ABP measurements did not differ in winter and summer (p = NS). Forty participants had complete data for winter-summer-next winter and HBP/ABP variability indices did not differ for both winters versus summer. These preliminary data suggest that BP variability is unaffected by seasonal changes in contrast to average BP levels.