Complex sentence: On September 15, Kalmaegi entered the South China Sea and intensified to a typhoon again, where it reached its peak intensity with sustained winds of 140 km/h (85 mph) while making its second landfall over Hainan Island.
Split into simpler sentences: On September 15, Kalmaegi entered the South China Sea and intensified again. The typhoon reached its peak strength, while making its second landfall over Hainan Island.