Climate and region of Halong Bay
The climate of Halong Bay follows a northern Vietnam weather pattern, similar to Hanoi but distinct from high-altitude areas like Sapa. The dry season runs from November to April, bringing cooler and more stable weather, while the rainy season lasts from May to October, bringing higher temperatures, increased humidity, and more frequent showers. Unlike central and southern Vietnam, where warm and tropical conditions persist year-round, Halong Bay sees clear seasonal changes with a cool winter and hot summer. As May marks the beginning of the rainy season, understanding these climate variations helps put its weather into perspective.
Weather in Halong Bay in May
May signals the beginning of the rainy season in Halong Bay, with temperatures rising to 24°C – 31°C (75°F – 88°F). The increase in warmth is accompanied by a noticeable rise in humidity, which often exceeds 85%. Rainfall picks up significantly, averaging 170 mm (6.7 inches) for the month, though showers are usually short-lived rather than continuous. The first summer storms may also appear toward the end of the month, bringing brief but intense downpours. Despite this, there are still plenty of sunny hours throughout the day, making it possible to enjoy outdoor activities between showers.
Being an early rainy-season month, May has a mix of both dry and wet days, but rain is still not as frequent as in peak summer months like July and August. While temperatures climb, it does not yet feel as hot as the peak of summer, and the bay remains calm on most days. This is the first month where the heat starts to become a factor, marking the shift toward the more tropical climate of northern Vietnam’s summer. You want to know what to expect in other months? Read our guide about Halong Bay weather per month.
Halong Bay cruise in May, is it worth it?
May is a good month for a Halong Bay cruise, but it also marks the beginning of the rainy season. Temperatures rise significantly, and humidity increases, making the air feel warmer than in April. Rainfall becomes more frequent, though showers tend to be short and scattered rather than lasting all day. The transition from the dry season means that while some days are sunny and clear, others may be cloudy or bring occasional downpours. Despite this, cruises continue to operate smoothly, and May is still before the peak of summer storms.
Pros of a May cruise
- Warm temperatures, making it great for outdoor activities.
- Sea remains calm, with most cruises running on schedule.
- More affordable than peak months, as it is not the busiest time.
- Still a mix of sunny and cloudy days, with some good weather periods.
Cons of a May cruise
- Rainfall increases, with a chance of brief downpours.
- Humidity is high, making the air feel hotter.
- Cloudy days are more frequent, though not every day is overcast.
Cruise activities in late Spring and early Summer
May marks the beginning of the hot season, making water-based activities a top highlight of any Halong Bay cruise. With temperatures rising between 24°C and 31°C (75°F – 88°F) and the sea warming to 26°C (79°F), swimming is now fully enjoyable. Many travelers take advantage of the warm water by jumping in directly from their cruise or visiting designated swimming areas on the beaches.
Kayaking in May is a fantastic experience, as the warmer air and water make it more comfortable than in the cooler months. However, as humidity begins to rise, it’s best to kayak in the morning or late afternoon to avoid the midday heat. Beach visits are also more appealing, as the hotter temperatures make relaxing on the sand or taking a swim refreshing. Ti Top Beach and Soi Sim Beach can get busier in May, but they remain a great stop during a cruise.
Trekking on Cat Ba Island is still possible, but the increasing heat and humidity make it more challenging. Hikers should start early in the morning to avoid the midday heat. Cycling is still enjoyable in shaded areas, such as Viet Hai village, but expect to sweat more than in earlier months. Visiting caves such as Sung Sot or Dark & Bright Cave is a great alternative to escape the heat, as the interiors remain cool throughout the year.
Events and festivals in May
May itself does not have any major festivals in Halong Bay, but it inherits the travel effects from Reunification Day (April 30th) and Labour Day (May 1st). These two holidays create a long public holiday for Vietnamese people, leading to a spike in domestic travel to Halong Bay. While the travel rush only lasts a few days, it can lead to higher prices and more crowded cruises during the first week of May.
Aside from this short peak in travel, May is a relatively quiet month in terms of festivals. There are no significant cultural or religious celebrations that would impact a cruise experience. This makes it a good time to visit for travelers who prefer fewer crowds once the holiday period is over.
Tips for visiting Halong Bay in May
May is a transition month, marking the shift from the dry season to the rainy season. While still warm and mostly dry, humidity increases, and occasional showers start to appear. With the right preparation, a cruise in May can still be a great experience.
What to bring
Since you can leave your main luggage at your Hanoi hotel, packing light for your overnight cruise is ideal. These items are essential for a comfortable trip:
- Light and breathable clothing, as temperatures are getting hotter
- Sunscreen and sunglasses, since sunny days are still common
- A light rain jacket or poncho, as sudden showers may occur
- A hat or cap, to protect yourself from the increasing sun intensity
- Sandals or water-resistant shoes, useful for beach stops and wet conditions
Cruise availability
May is not a peak travel month, but the Labour Day holiday on May 1 combined with Reunification Day (April 30) creates a short-term surge in domestic travel during the first week of the month. After this period, May is quieter, making it a good time to book cruises at a better price compared to peak season.
While international tourist numbers remain steady, they are lower than in March and April, meaning you can often find last-minute cruise deals outside of the holiday period. However, since May marks the beginning of the rainy season, travelers should be prepared for occasional rain.
Complete Halong Bay travel guide
May offers a mix of warm, sunny days and occasional rain, making it important to plan your trip wisely. If you’re looking for alternative bays like Bai Tu Long or Lan Ha Bay, a scenic flight over Halong Bay, or information on beaches, caves, and floating villages, our Halong Bay travel guide provides all the details you need.
