Halong Bay attracts visitors year-round with peak season between late May and early August. January to March is often cool and drizzly, and the ensuing fog can make visibility low, but adds bags of eerie atmosphere. From May to September tropical storms are frequent, and year-round tourist boats sometimes need to alter their itineraries, depending on the weather. November's sunny blue-sky days and lack of crowds make it the best time to make a beeline here.