Simplify the following text for a Grade 4 native English-speaking person.
Original: Charley lasted from August 9 to August 15 , and at its peak intensity it attained 150 mph ( 240 km\/h ) winds , making it a strong Category 4 hurricane on the Saffir-Simpson Hurricane Scale .
Simplified: Charley lasted from August 9 to August 15 . Its strongest winds were 150 mph ( 240 km\/h ) .