September in Halong Bay: Weather and Event Guide

September in Halong Bay: Weather and Event Guide

  • In September the weather starts to slowly cool down.
  • But, temperatures reaching over 30 degrees are still not uncommon.
  • Even though rainfall might still be frequent, it’s not as heavy as in August.
  • September marks the end of the tourist off-peak season.
  • The weather can still be quite agreeable at times so it’s a great month for water activities like swimming, kayaking, and snorkeling.

September Weather In Halong Bay

It’s the end of summer and even though things are cooling down, it’s still quite hot! Be sure to expect some extremely hot days, with the mercury hitting well over 30°C. Humidity levels do start to slightly decrease in September though, with an average level of about 72%. It rains less in September compared to August but with 190mm of rain in 14 days, it still can be quite wet!

MonthHigh / Low (°C)Average rainfall (MM)Rain Days
September31° / 24°190 mm14 days

September Weather Average 

Pros and Cons for Visiting in September 


  • There’s less rain in September but beware, a heavy downpour or two may still occur. 
  • Temperatures are still nice and warm in September making it a good occasion to get your swimsuit out.
  • Popular activities include kayaking, snorkeling, and swimming. September is the end of the off-peak season so there are still not a lot of tourists visiting Halong Bay.


  • Stormy weather is still a possibility. Some cruises may still operate during bad weather, but a storm can hinder the planned activities and excursions. 
  • The temperatures during September can be still quite hot, this is not for everyone. 


On September 2nd Vietnam celebrates the Independence Day, this is a full public and bank holiday so expect some businesses to be closed.

Fireworks on the Independence Day in Vietnam. 

What to pack

For your September visit, you should pack light clothes, don’t bother packing anything too heavy or warm as you probably won’t use them. As September is still a great time for water activities, be sure to bring your swimming gear. The sun can be quite menacing, it’s important that you bring adequate protection from the sun - a high factor sunscreen is recommended.


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