September has a comfortable weather with a cool climate. It is also considered one of the ideal time to visit Halong Bay as the temperature is just right while tourists are less crowded than the previous months.

May marks the start of a hot summer although the heat is still in the endurable zone. May is known as the best month to travel to Halong Bay thanks to the perfect weather for water activities.

April is a good month to visit Halong Bay, the weather is just right to organize an outdoors trip, and probably it is the best time for doing photoshoot of the bay thanks to the generous amount of sunshine.

March sees noticeable changes in climate from cold winter to humid spring. It is a good time to visit Halong Bay with more chance for water activities and nice sunshine for photography.

Warmer than January, February making it a more comfortable to travel to Halong Bay. But a well preparation of warm clothes is still recommended as winter has not came to the end yet.