After passing near Guam , it strengthened quickly and reached its highest winds of 305 km\/h ( 190 mph ) and a worldwide record low barometric pressure of 870 mbar ( hPa , 25.69 inHg ) on October 12 . After passing Guam , it rapidly intensified and reached peak winds of 305 km\/h ( 190 mph ) and a worldwide record low sea-level pressure of 870 mbar ( hPa , 25.69 inHg ) on October 12 .