Sipadan in September

March through October gives you the best visibility and calmest seas. April to July hits the sweet spot - visibility often reaches 40+ meters and rainfall stays minimal. But here's what matters most: dive permit availability. Book your Sipadan permits at least 2-3 months ahead through registered dive operators. The Malaysian government strictly limits daily visitors to protect the reef. Avoid November through February unless you enjoy diving in washing machine conditions - northeast monsoons bring rough seas and reduced visibility. Water temperature stays around 27-29°C year-round, so you'll only need a 3mm wetsuit.