 Early on September 1 , Hurricane Luis strengthened into a Category 3 hurricane with winds of 115 mph ( 185 km / h ) ; upper @-@ level outflow continued to improve throughout the day , allowing further intensification . Maintaining its structure , Luis further intensified to a Category 4 hurricane with winds of 135 mph ( 215 km / h ) . Subsequent to doing so , its intensity remained steady for 42 hours while it tracked nearly due west . Early on September 3 , satellite intensity estimates indicated that the storm strengthened slightly , attaining its peak winds of 140 mph ( 225 km / h ) at around 0600 UTC . Continuing on a westward track , the forward motion of the hurricane decreased to 13 mph ( 20 km / h ) later on September 3 . When Luis was about 690 mi ( 1 @,@ 110 km ) east of the Lesser Antilles , a Hurricane Hunter reconnaissance flight into the storm confirmed satellite intensity estimates . Flight level winds around the eye of Luis were recorded at 165 mph ( 265 km / h ) , which corresponds to surface winds of 140 mph ( 225 km / h ) and a minimum barometric pressure of 944 mbar ( 27 @.@ 87 inHg ) . 
