Het weer in Ko Lanta Yai in december

December opens the high season rather than sitting in the middle of it, and regulars describe a month that improves as it runs. Early on there are showers, sometimes rain most afternoons and heavy with it, though the mornings are usually fine; by late December and into January there is very little rain if any. They also make the case that a short downpour here is welcome because it takes the heat out of the day. Our row is the average of those two halves: 140mm across 14.9 days under 31.5C that reads as 36C at 85 percent humidity. Crowds run the other way - this is peak season and it is busy. The record: 23.4C nights, 9 hours of sun, a 29.2C sea and AQI 38.

Ko Lanta's forum confirms August is genuinely rainy season on the Andaman coast, with rough, stormy seas as much a factor as the rain itself - but experiences vary widely. One regular visitor who'd been six times including in low season said they'd only hit real rain once; another described a typical day as sunny with a quick thunderstorm rolling through in the afternoon or evening rather than a washout. Many smaller resorts close for the season from June through early November, though the mainland ferry keeps running year-round regardless.

Forum posters consistently name January and February as by far the driest, most reliable months on Koh Lanta, with several repeat visitors saying they've barely seen rain across multiple separate January/February trips - one describing a full three weeks without a drop. One visitor specifically reported a February day at 32C with not a cloud in the sky. Posters do note this isn't an absolute guarantee: some travelers have hit a rainy, overcast stretch that dampened snorkeling plans even within this generally dry window, but the clear consensus is that February sits at the reliable peak of the island's dry season.