Vanuatu (Espiritu Santo) in September

April through October brings Santo's dry season – your best bet for consistent diving conditions and minimal rain. Water visibility stays excellent, typically 30-40 meters, and the trade winds keep temperatures comfortable. May through September offers the sweet spot. Rainfall drops to almost nothing, humidity stays bearable, and the southeast trade winds provide natural air conditioning. This is peak season, so book accommodations early and expect higher prices. November through March brings the wet season and cyclone risk. Heavy rains can wash out roads and cancel diving trips. But if you can handle the humidity and occasional downpour, you'll find better deals and fewer crowds. Water temperature actually peaks during these months at 28-30°C. Cyclone season officially runs December through April. While direct hits are rare, even nearby storms can create dangerous conditions for water activities. Check weather forecasts carefully if traveling during these months. The shoulder months of April and October offer the best balance – decent weather, fewer crowds, and moderate prices. Water visibility might not be quite as good as peak dry season, but it's still excellent by most standards.