The stormed formed from a non-tropical system between Bermuda on Cape Cod , Massachusetts that developed on July 31 with good conditions for further development . The storm had maximum sustained winds of 50 mph ( 80 km\/h ) and began to move quickly northeastwards into colder water temperatures . It developed on July 31 from non-tropical origins between Bermuda and Cape Cod , and with favorable conditions , Chantal rapidly attained peak winds of 50 mph ( 85 km\/h ) .