Dear Tom,
Does Hudson Bay have any effect on Chicago weather?
—Bill Peters, Beach Park
Dear Bill,
Though Hudson Bay is more than 1,000 miles to our north, its icy waters do play a role in Chicago’s weather. That region is a frequent host to large, stationary high pressure systems that keep a sustained northeast flow of air into the Midwest and Chicago. The air of arctic origin is not only cold, but also dry and can bring extended periods of cool and dry weather to Chicago during spring, summer and fall. When this type of flow occurs in winter, the result is often a prolonged period of cloudy, snowy weather. The snow is usually light due to lack of moisture except where the lake-effect from the Great Lakes enhances totals. When low pressure is parked over Hudson Bay in winter Chicago can be in line for major arctic outbreaks and sustained periods of severe cold.
