Luang Namtha in December

November through March gives you the best weather - dry, cool mornings that warm up to perfect hiking temperatures. December and January can get surprisingly chilly at night, especially in the mountains, so pack layers. April and May turn brutally hot before the rains arrive in June. The wet season lasts until October, making jungle treks muddy and river crossings dangerous. But here's the thing - some of the most spectacular waterfalls only flow during rainy season. If you can handle the humidity and occasional downpour, July and August offer fewer crowds and lusher jungle scenery.