Long-Term Winter Temperature Trends in the Southeastern United States

This study examines maximum and minimum temperatures in the southeastern United States during the winter months, 1910-1987. Our goal is to understand regional winter temperature trends in the context of global temperature and circulation patterns. To this end, we identify regional winter temperature patterns, relate them to continental-scale upper-air flow, and measure the relationship between mean temperature and interannual temperature variability at different spatial scales. At a regional level, we find a decrease in both maximum (1.06° C) and minimum (1.63° C) winter temperatures during the study period. All but 18 of the 156 stations investigated experienced a maximum winter temperature decrease, but these trends are significant (α = 0.01) at only 36 stations. Minimum winter temperature dropped at all except 14 stations, with decreases significant (α = 0.01) at 80 stations. While there is some correlation with anomalous upper-air circulation during individual months, no significant relationship was found between mean polar or hemispheric winter temperature and interannual variability in the region. This finding suggests that unusually cool southeastern winters frequently are caused by regional circulation anomalies that are not necessarily found at the hemispheric or global scale.