Tioman Island in July

March through September is prime time when the South China Sea calms down and visibility underwater hits 20+ meters. April and May are perfect - hot days, calm seas, and fewer crowds than the summer holidays. June through August brings Malaysian school holidays and higher prices. Book accommodation well ahead if you're traveling during these months. The weather is reliable, but expect more families and noise. September is the sweet spot. Post-holiday calm returns, but the weather stays dry. This is when locals visit, which tells you something. Restaurant prices drop back to normal, and you can actually get a table at popular spots without waiting. October through February is monsoon season. Most resorts close completely from November to March. The few that stay open offer rock-bottom prices, but you're gambling with weather. Rough seas cancel ferry services regularly, and diving is hit-or-miss. Turtle nesting season runs May through September, with peak activity in July and August. Juara Beach is the main nesting site, but remember that turtle watching requires patience and luck.