Simplify the following text for a Grade 9 native English-speaking person.
Original: It moved northwestward , and within an environment of light wind shear and warm waters it steadily strengthened to reach peak winds of 165 mph ( 265 km\/h ) on September 11 .
Simplified: It moved northwestward , and it steadily strengthened to reach peak winds of 165 mph ( 265 km\/h ) on September 11 .