Ivan strengthened fast and by the end of the day on September 5 it became a category 3 hurricane .
Later that day , the storm intensified rapidly , and by 5 p.m. EDT ( 2100 UTC ) , Ivan became a Category 3 hurricane with winds of 125 mph ( 201 km\/h ) . The National Hurricane Center said that the rapid strengthening of Ivan on September 5 was unprecedented at such a low latitude in the Atlantic basin .