The dry season — November to May — is the best time to visit. The roads are passable, the bush is navigable, and the mangroves are at their most photogenic with clear water. January and February are the coolest and most comfortable months.
The wet season (June to October) brings heavy rains that can make laterite roads impassable and flood low-lying areas. It is also the most beautiful time visually — everything is intensely green, the rice paddies are full, and the rivers run high — but getting around is genuinely difficult. Mosquitoes are at their worst from July to September.
The dry season also coincides with the fishing festival season, when villages hold ceremonies marking the start of the fishing calendar. Ask locally about dates — they vary by village and are not advertised widely.