Halong Bay Weather in September

September signals the arrival of autumn on Halong Bay and is still in the rainny season. The temperatures and rainfall are on a gradual decline. In addition, the weather is rather hot in the daytime and cools down at night.

Halong Bay Weather in September

  • In September, the weather starts to fall slowly but there are some days when the high temperatures reach over 30 degrees.
  • Even though rainfall is frequent, it is 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 is a great month for water activities like swimming, kayaking, and snorkeling.

The transitional month with acceptable precipitation and humidity level makes Halong Bay quite comfortable and not as humid and stuffy as the previous months. The volume of tourists recovers steadily. This type of weather is worth planning a trip and engaging in outdoor adventures like cruising, mountain trekking, and biking.

September Weather In Halong Bay


September in Halong Bay is the end of summer and even though things are cooling down, it’s still quite hot! The average temperature is 28°C and hardly lower than 22°C. There are some extremely hot days, with the temperature hitting over 30°C.

The sea water temperature also declines compared to the previous month, making it comfortable and appealing to swim.


Halong Bay in September enjoys an average number of 6 sunshine hours per day. The sun is still strong so you really need sun protection when being out.


The humidity levels do start to decrease slightly in September though, with an average level of about 72%.


It rains less in September compared to July and August. The average rainfall is 190mm falling over 14 days, thus, it can be quite wet!

Historical weather data

MonthHigh / Low (°C)Average rainfall (MM)Rain Days (≥2mm)
September (2020)33.66°C (92.59°F) / 21.42°C (70.56°F)401.61mm / 15.81in19 days
September (2019)32.64°C (90.75°F) / 22.44°C (72.39°F)246.97mm / 9.72in12 days
September (2018)34.68°C (94.42°F) / 24.48°C (76.06°F)54.19mm / 2.13in7 days
September (2017)32.64°C (90.75°F) /  26.52°C (79.74°F)140.44mm / 5.53in15 days

September Weather Average 

Pros and Cons of visiting Halong in September 


  • There is less rain in September but beware, a heavy downpour or two may still occur.
  • Temperatures are 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 will be more and more tourists coming to Halong Bay.


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

Events in Halong Bay in September

On September 2nd Vietnam celebrates Independence Day. This is a full public and bank holiday so expect some businesses to be closed. Halong Bay can be overcrowded with domestic visitors on that day so you should book cruises and services far in advance to avoid price rises.

Fireworks on the Independence Day in Vietnam. 

Mid-Autumn Festival which falls on the 15th day of the eighth lunar calendar is one of the most popular festivals in Vietnam. This traditional festival is very much like Halloween and Thanksgiving in Western countries. On this occasion, children carry colorful lanterns and join the parade on the streets. All Vietnamese families also decorate the altar with many fruits and moon cakes to wish for a prosperous harvest.

Mid-Autumn by year:

Mid-Autumn Festival 2022Saturday , September 10
Mid-Autumn Festival 2023Tuesday ,September 17
Mid-Autumn Festival 2024Friday ,September 29
Mid-Autumn Festival 2026Friday ,September 25
Mid-Autumn Festival 2027Wednesday, September 15

Best things to do in Halong Bay in September

Swimming and kayaking

Swimming and kayaking definitely top the list of must-try activities on Halong Bay in September. It is because the temperature is more endurable for getting outdoors. There are also less rains and storms so you enjoy the beauty of the bay in sunny weather.

Overnight Cruise

The possibility of downpours, storms, and typhoons reduces significantly in September so you can enjoy an overnight cruise on Halong Bay without much worries about bad weather conditions. Halong Bay is best to explore for three days to fully check-in well-known attractions and experience exciting activities. Onboard entertainment is also great with morning tai chi, sunset party, squid fishing, and cooking class.

Seaplane tour

Taking a seaplane tour will bring you an extraordinary experience to contemplate the breathtaking beauty of Halong Bay from altitudes from 150 to 300 meters. The tour is provided by Hai Au Aviation company and lasts 25 minutes.

Mountain trekking

Situated 40km from Halong Bay, Yen Tu Mountain is a well-known tourist attraction attracting many pilgrims and sightseers to visit and admire the views.  At the foot of the mountain, there is a craft village where you can explore many unique traits of Vietnamese culture. On the way trekking to the peak of Yen Tu Mountain, you will pass through many temples and the most popular one is Dong Temple at the top.

Alternatively, you can choose another less challenging route to the top of Titop island. This destination is mostly included in the cruise itinerary to Halong Bay. You will spend 30 minutes climbing to the top and enjoy panoramic views of Halong Bay.

Activity ratings


Best places to do

Pros and cons in September



Titop Island, Ba Trai Dao Beach, Ao Ech area

- Pros: hot weather, low humidity

- Cons: sudden rains can affect your swim



Luon Cave, Dark & Bright Cave, Tung Sau Pearl Farm, Ao Ech Area

- Pros: hot weather, high number of sunshine, low humidity

- Cons: sudden rains can affect your trip


Overnight cruise

 Orchid cruise, Stellar of the Seas, Elite of the Seas

- Pros: good weather condition

- Cons: high season, can be overcrowded, prices can be higher


Seaplane tour

 Hai Au Aviation (

- Pros: bright and sunny sky, clear vision, cooler temperature when enjoying the bay from above

- Cons: high season, the service can be easily fully booked


Mountain trekking

Yen Tu Mountain, Titop Island

- Pros: a clear vision for panoramic views of the surrounding landscapes

- Cons: trekking is not possible during rainy days



Viet Hai Village, Cat Ba Island

- Pros: less rains and storms so you can cycle in dry weather

- Cons: this activity is not suitable for everyone and can make you tired.


What to pack in September

For your September visit, you should only pack light clothes, sandals, and sun hat. Warm and thick clothes are not needed. As September is still a great time for water activities, be sure to bring your swimming gear. The sun can be quite strong, so it is important that you bring adequate protection items from the sun - a high-factor sunscreen is recommended.

Recommended packing list by activities


September weather 

Packing list

Swimming & kayaking

- Hot

- Low humidity

- A lower chance of storms

- Sunscreen

- Sun hat

- Light clothes

- Sandals

- Bath towels

- Swimsuits

Overnight cruise

- Hot and rather dry

- Rains and stormy weather are less often

- Light clothes

- Sunscreen

- Swimsuits

- Camera

Seaplane tour

- Hot, dry weather

- Strong sunray

- A lower chance of rains and storms

- Light clothes

- Sunglasses

- Sunscreen

- Camera

Mountain trekking

- Hot and sunny weather

- There are still some sudden and unexpected rains

- Sunscreen

- Sports shoes

- Sun hat

- Camera

- Insect repellent

- Bottles of water

- Light clothes


- Hot and sunny

- Lower chance of rains

- Sports shoes

- Insect repellent

- Bottles of water

- Sunscreen

- Sun hat

Local tips

Generally, the weather in Halong Bay in September is more suitable for cruising and other outdoor trips but it is also the peak tourist season so you should keep in mind some following tips:

  • Halong Bay can be crowded with domestic travelers on public holiday so you should check your departure date and book the services far in advance.
  • September is the high season so expect that the prices can increase.
  • Although the weather is ideal to travel, it is still essential to check the weather forecast carefully prior to your arrival.
  • This shifting season calls for light clothing and sun protection.


1. Is it worth planning a trip to Halong Bay in September?

September starts the peak tourist season in Halong Bay and the weather is much more enjoyable for a trip. There are fewer occassions of storms and rains also do not last long. In addition, some cruise operators and other services still offer good deals and promotions so you can enjoy high-quality services at a much lower price.

2. Does it rain a lot in Halong bay in September?

The rainfall level decreased substantially in September to only 190mm on 14 days. The chance that you can experience sightseeing trips in good weather is very high.

3. Is it better to go to Halong bay in September or October?

Both September and October are suitable for a trip to Halong Bay. However, while October offers better weather conditions, the bay can be crowded with tourists.

4. Do I need to book the service in advance?

Definitely yes, September is the early peak season in Halong Bay and cruises and services can be fully booked quickly so you need to book in advance. Moreover, many cruise operators continue to offer promotions so you can expect a chance of booking at a cheaper price.

5. What are alternative activities can I do if I do not want to go outside?

In case you do not want to go out, you can choose to relax on the cruise and enjoy bay views. Other indoor activities you can try in Halong are visiting museums and playing in the Sun World entertainment complex or visiting Tuan Chau Island and Tuan Chau Park.

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