It reached its peak intensity on August 1 , with winds of 135 mph ( 215 km\/h ) and a central pressure of 946 millibars , making it the strongest hurricane of the season . It reached its peak intensity on August 1 , with winds of 135 mph ( 215 km\/h ) and a central pressure of 946 millibars , making it the strongest hurricane of the season at a Category 4 strength .