What do you think our weather patterns would be like if the Great Lakes did not exist?
—Dana Kennedy, Ottawa, Ill.
Chicago’s climate would be much more “continental.” That is, its weather would be more prone to extremes of temperature and, to a lesser extent, of precipitation. Events such as the cooling lake breeze in the summer and lake-effect snow would be gone. The climate would be more like that of Iowa. The lakes represent a massive heat source in the winter, causing passing low-pressure systems to delay their departure, with the result that wind, cloudiness and occasionally bursts of light precipitation linger. The opposite effect prevails in the warm season. The presence of the Great Lakes tends to delay the onset of rain and sometimes to delay its departure.