 On September 28 , Isaac peaked as a low @-@ end Category 4 hurricane with winds of 140 mph ( 220 km / h ) . Following its peak intensity , Isaac began to weaken immediately thereafter , while turning north @-@ northwestward . Eventually , the storm turned northward before re @-@ curving north @-@ northeastward . Further weakening occurred after Isaac moved over decreasing sea surface temperatures and dropped down to Category 1 intensity by September 30 , while accelerating northeastward . On October 1 , Isaac was downgraded to a tropical storm shortly before transitioning into extratropical later that same day . The extratropical remnants affected the British Isles between October 3 and October 4 . Minimal impact was reported from Isaac . One fatality occurred when a passenger drowned after his boat capsized due to large waves produced by Isaac offshore Long Island , New York . 
