Considered by the National Weather Service to be the most devastating blizzard to ever hit the Great Lakes — more than 235 people were killed and 18 ships wrecked — the November 1913 storm was caused by a mixture of Arctic air with a low-pressure system. There was such a high number of shipwrecks because of the time of year; if the storm had occurred later in the season, the lakes would have been closed to traffic. The storm, which raged for nearly five days and caused about $5 million in damage, saw hurricane-force winds of up to 62 m.p.h. (100 km/h) and waves that reportedly reached up to 35 ft. (10 m) in height.