Climate and region of Halong Bay
Halong Bay’s climate follows a seasonal pattern typical of northern Vietnam, with similarities to Hanoi but without the extreme temperature shifts seen in high-altitude destinations like Sapa. The dry season, from November to April, is cooler and more stable, while the rainy season, from May to October, brings warm temperatures, high humidity, and increased rainfall. Unlike central and southern Vietnam, where the climate remains warm and tropical year-round, Halong Bay experiences distinct shifts between winter and summer. Since September marks the late rainy season, understanding these broader climate trends provides useful context for planning a visit.
Weather in Halong Bay in September
September marks the transition between the peak rainy season and the gradual return of drier conditions. Temperatures remain high, ranging from 25°C to 32°C (77°F – 90°F), but humidity starts to decrease slightly compared to the peak summer months. Rainfall remains substantial, averaging 250 mm (9.8 inches), but the frequency of showers begins to decline toward the end of the month. Tropical storms are still a possibility, though they become less common as October approaches. Days tend to be a mix of sunshine and clouds, with occasional bursts of rain.
While September is still considered part of the rainy season, the second half of the month often sees fewer storms and more stable weather patterns. The transition to autumn begins, bringing slightly more comfortable conditions, although high humidity can still make the air feel heavy. Travelers visiting in September should be prepared for a mix of rain and sunshine, but also the possibility of last-minute cruise schedule changes due to storms. Interested to know what all the seasons of Ninh Binh are? Read our guide seasons in Halong Bay explained.
Halong Bay cruise in September, is it worth it?
A cruise in Halong Bay in September is a mix of advantages and challenges, as it is a transitional month between the rainy and dry seasons. The first half of the month can still bring heavy rain and the occasional storm, while the second half sees more stable weather and fewer disruptions. Temperatures start to cool slightly compared to the peak summer months, but humidity remains high. September is also one of the quieter months for tourism, meaning lower prices and fewer crowds, which can make for a more relaxed cruise experience.
Pros of a September cruise
- Cheaper cruise rates, as it is still low season.
- Fewer tourists, allowing for a quieter experience.
- Gradual improvement in weather, especially later in the month.
- Warm sea temperatures, still good for swimming.
Cons of a September cruise
- Early September still sees frequent rain, though it decreases later.
- Storms are still possible, occasionally affecting cruise operations.
- Humidity remains high, though slightly less than in August.
- Weather can be inconsistent, with a mix of sunny and rainy days.
Cruise activities in late rainy season
September is a transition month, meaning the rainy season is still active in the first half, but conditions start improving later in the month. Temperatures remain warm, averaging 25°C to 32°C (77°F – 90°F), and the sea temperature is around 29°C (84°F), making swimming an excellent activity on dry days. However, sudden rain showers or storms can still occur, especially in the first weeks.
Kayaking is a great way to explore the bay, as long as you plan around potential rain showers. The calm waters make paddling enjoyable, but humidity is still high, so it’s best done in the morning or late afternoon. Beach visits are a good option on sunny days, as the warm water is perfect for swimming, but occasional rain may limit time on the sand.
Trekking on Cat Ba Island is still not ideal, as trails can be wet and muddy, especially after rain. Cycling in Viet Hai village is more feasible later in the month, as rainfall decreases. Cave visits remain an excellent activity, providing shelter from both heat and rain while offering a fascinating look at Halong Bay’s natural formations.
Interested in learning more about the seasons? Check out Halong Bay in rainy season to see if it’s worth visiting.
Events and festivals in September
September is one of the first months after the summer school holiday and marks the beginning of a new travel season. However, it does include a major national holiday and an important cultural festival that travelers should be aware of.
- Vietnam National Day (September 2nd) – This public holiday celebrates Vietnam’s independence, and it is officially recognized with a day off across the country. While Halong Bay itself does not host major celebrations, many locals use this long weekend as an opportunity to travel. As a result, there is a temporary peak in domestic tourism, leading to busier cruises and slightly higher prices around this date.
- Mid-Autumn Festival (dates vary, usually late September or early October) – The Mid-Autumn Festival is one of Vietnam’s most traditional celebrations, focusing on children and family gatherings. Lanterns, lion dances, and mooncakes are an important part of this event. While it is widely celebrated in cities and towns, Halong Bay cruises do not host traditional Mid-Autumn celebrations. However, many boats decorate with lanterns, and some cruises offer mooncakes as a special treat. For travelers who want to fully experience the festival, visiting a city like Hanoi before or after a cruise is a great option.
Since the Mid-Autumn Festival sometimes falls in early October, visitors should check the exact date if they are interested in seeing the celebrations.
Tips for visiting Halong Bay in September
A cruise in Halong Bay in September can be more enjoyable if you plan ahead and pack the right essentials. Here are some useful tips to make your trip as smooth as possible.
What to bring
If you’re doing a short cruise from Hanoi, you can leave most of your luggage at your hotel to make traveling easier. Be sure to pack:
- Light clothing, as temperatures are still warm
- A rain jacket or poncho, since sudden rain showers are possible
- Waterproof shoes or sandals, useful for wet conditions
- Bug repellent, as mosquitoes are still common in humid weather
- A dry bag, to protect valuables from unexpected rain
Cruise availability
September is not a peak travel month, so cruises are more available and often more affordable compared to high-season months. However, Vietnam National Day on September 2nd brings a temporary surge in domestic travel, leading to a short period of higher prices and busier cruises around this time.
Outside of this holiday, September is a great time to find last-minute deals, but as the rainy season is still present, it’s wise to book with a flexible cancellation policy in case of unexpected weather changes.
Complete Halong Bay travel guide
While we’ve covered key travel tips for September, Halong Bay has much more to offer. Whether you’re considering alternative bays like Bai Tu Long and Lan Ha Bay, visiting Cat Ba Island, taking a scenic flight, or exploring hidden caves and floating villages, there are many ways to enhance your trip. To plan the best experience, check out our Halong Bay travel guide.
