Although you can visit Ha Long Bay all year round, you'd better plan your cruise carefully. Bad weather affects the visibility and can even spoil your trip. The best time to visit Ha Long Bay starts is from March to June;, avoid crowded public holidays (30 April 30 and 1 May). June to September is low season so you can get better deals but pay attention to storm forecasts. October and November is high season again and it is still sunny. December is cool, cloudy but dry while January and February are cold, foggy and drizzly. The showers will hide the splendor of the bay.