Dry and warm throughout the country (although it can get a little cold in the north and on Bolaven Plateau). The river levels are perfect for cruising, and flora/fauna are in abundance. Rates spike and hotels fill up over Christmas and New Year, so book in advance.
A little wet but in short spells. Expect blazing hot days, yet pleasant nights. River levels drop a little (nor affecting cruising), and a haze develops over the country as farmers slash-and-burn their fields. Tourists throng, but hotels are easier to find and book. Recommend combining the plains with the cooler Bolaven Plateau, to offset the heat.
The wet season kicks off in July, peaking in August. Temperatures soar when it is not raining. The rivers start to fill up again and remote areas can be difficult to access. However, towards end-September, the sun begins to peak through, inviting tourists in to enjoy the lush landscape and cascading waterfalls.