The climate is humid subtropical (Köppen: Cfa), but all around Greater St. Louis has a humid continental climate (Dfa) through the USA isoterm, with a winter that sustains in the coldest month temperatures below 0 °C more easily, clear evidence of an urban heat island, which in the future may cover an even larger area and agglutinate cities and villages to the south.
The climate is humid subtropical (Köppen: Cfa), but Greater St. Louis has a humid continental climate (Dfa) through the USA isoterm, with winter temperatures below 0 °C in the coldest month, suggesting an urban heat island that might grow and integrate cities and villages to the south.