Ningaloo Reef in December

March through August delivers the holy grail: whale shark season. These gentle giants follow the coral spawning, with peak numbers typically in April and May. Water visibility hits 30+ meters during these months, and you'll encounter manta rays, reef sharks, and massive schools of fish. But here's the trade-off - accommodation prices double, and you'll need to book tours and lodging 6 months ahead. September through February brings calmer conditions and better weather for camping, but no whale sharks. The coral spawning in March creates temporarily murky water but triggers incredible marine activity. Avoid December and January if you can - cyclone season brings unpredictable weather and rough seas.