Ha Long Bay in August: the wettest month

August is the wettest month on Ha Long Bay, and the reviews barely register it. Ten years of modelled weather average 456 mm of rain, yet 66 of the 1,469 reviews posted in August give one or two stars, 4.5%, the same share as across the year. The catch is the storms. August has more reviews mentioning a cancellation than any other month, and in 2026 a closure began at 07:00 on 22 August.

Review figures come from 13,074 dated reviews of 76 boats, posted up to 25 October 2026 and counted on 28 October 2026. Three boats whose full Google history we hold count only their 700 most recent reviews, so no single boat outweighs the rest. A review’s date is the day it went up, which can be days or weeks after the trip.

What is the weather like in August?

Hot and wet, with real sun between the showers. These are averages for 2016 to 2025 from ERA5 reanalysis via Open-Meteo, a model grid about 25 km wide that smooths out the extremes.

August, 2016–2025	Average
Daytime high	30.6°C
Night-time low	26.7°C
Warmest August day in the ten years	35.6°C (4 August 2025)
Coolest August night in the ten years	24.0°C (25 August 2025)
Days with 1 mm of rain or more	25.3
Days with 20 mm of rain or more	7.1
Rain in the month	456 mm (181 mm in the driest year, 622 mm in the wettest)
Wettest August day in the ten years	111.7 mm (3 August 2019)
Sunshine	8.0 hours a day
Sea-surface temperature	31.7°C (three Augusts)

The middle of the month is the dampest. From 11 to 20 August an average year brings 172 mm, the most of the three ten-day stretches, and sunshine falls to 6.9 hours a day, against 8.0 hours in the first ten days and 9.0 in the last eleven. Against July, August has about 100 mm more rain and an hour less sun a day at much the same heat.

August 2024 had 181 mm and August 2022 had 622 mm. The wettest single months in the record were a September at 717 mm and a July at 687 mm, as our weather guide sets out. Nights barely cool. The low stays at 26°C or above on about 20 August nights, so the cabin air conditioning will run until morning.

Is the sea rough in August, and can you swim?

The water is warm and usually calm: 31.7°C on average over three Augusts, from 28.7°C to 33.0°C. Across four Augusts the highest wave of an average day was 0.40 m on open water, and the biggest of the 124 days reached 1.36 m. Our seasickness guide covers the motion guests do notice.

Wind is the risk, and it arrives with storms. Gusts of 50 km/h or more came on 34 August days in ten years, fewer than July’s 57, but 13 of the decade’s 50 windiest days fell in August. The worst was 25 August 2025, with a gust of 94 km/h and 97.4 mm of rain.

Ten reviews in our log describe jellyfish in the water, six of them posted from June to August 2026. One guest posting on 12 August 2026 says they could swim while they waited for a kayak, at the risk of there being lots of jellyfish in the area. Ask the crew before you go in.

What happens if a storm closes the bay in August?

The boats stop from an hour the province names, and your operator does not choose it. For storm no. 4 of 2026, Quang Ninh’s Department of Agriculture and Environment asked for sightseeing and overnight stays to stop being licensed from 07:00 on 22 August 2026, as Nhân Dân reported that day. The median Hanoi pick-up across the 52 operator timetables that print one, counted on 16 October 2026, is 08:00, an hour after that stop began. Licences return only after the final storm bulletin. What changed on Ha Long Bay in 2026 lists this year’s stops with their hours.

August has more reviews mentioning a cancellation or a schedule change than any other month, 10 of 1,469, with April next on eight, and nine of the ten give one star. At least five describe trips called off for weather and were posted between 18 and 31 August 2025. Two of them call the weather understandable and object to how the news came. One guest was driven three hours to an office, a transfer they had paid for, and kept waiting an hour and a half before being told the cruise was off. Another checked in at a lounge in Ha Long at 11:00 and learned at 13:00, from other guests, that the trip was cancelled.

The tenth, at five stars, is from a guest whose date was cancelled for bad weather: the booking office offered a full refund or a new date, and rebooked them later that week.

The wettest day in our weather record, 7 September 2024, when Typhoon Yagi hit, came a week after the month ended; our September guide covers it. Before paying for a late-summer trip, read the cancellation terms for a closure on your date.

Do August reviews score worse than other months?

No, by any margin we can separate from chance. On the three complete years, 2023 to 2025, 44 of 651 August reviews (6.8%) sit at one or two stars against 357 of 6,330 (5.6%) for all months, a gap that is also within chance.

August posted in	Reviews	One or two stars	That whole year
2023	70	7 (10.0%)	9.4%
2024	216	7 (3.2%)	6.2%
2025	365	30 (8.2%)	4.8%
2026	778	21 (2.7%)	2.9% (to 25 October)

The thinner Augusts of 2016 to 2022 add 40 reviews and one low score.

August 2025 is the outlier. Its 30 low scores in 365 reviews, 8.2%, compare with 169 in 3,764 (4.5%) for the rest of 2025, a difference unlikely to be chance. Two clusters stand out: nine one-star reviews landed on one boat’s listing on 18 August 2025, and four on another boat’s listing on 30 August. Reviews posted from 21 to 31 August hold 28 low scores in 390, 7.2%, against 38 in 1,079 (3.5%) for the first twenty days, and 14 of those 28 come from 2025.

Of the 52 low August reviews we have classified by subject, 15 mention the transfer, against 64 of 438 low reviews in other months, and six of those 15 were posted between 18 and 31 August 2025. Fifty-two is a small sample.

Is August busy, and what about the 2 September holiday?

Busy, though not the busiest: August is second of the twelve months by reviews posted, 1,469, behind October, a count that tracks guest numbers only loosely. Crowd words turn up in 20 of the 1,263 August text reviews, 1.6%, against 2.3% across the year, a gap small enough to be chance.

The month runs straight into Vietnam’s National Day. In 2027 the holiday lasts from Thursday 2 September to Sunday 5 September, as Tuổi Trẻ reported on 11 October 2026. Two boats we list print a 2 September surcharge on their own sites, both read on 22 October 2026. Aqua of the Seas lists $25 a person on its two-day itinerary page, which carries rates for 1 May to 30 September 2026 and for 1 October 2026 to 30 April 2027. Cozy Bay Grand lists 200,000 dong, about $8, a person in its 2026 price guide. For 2027, ask for the figure and whether 3 to 5 September count.

Which boats did well in August?

Ambassador Signature, Nostalgia and Orchid Trendy came through August without a low score. Among the 34 boats with 100 or more reviews counted over at least a year, they are the only three with 40 or more August reviews, none at one or two stars, and a five-star share of 90% or more across the reviews we count, as of 28 October 2026.

Boat	Bay	August reviews	One or two stars in August	All reviews counted	Five stars, all reviews counted
Ambassador Signature	Lan Ha	97	0	547	97.1%
Nostalgia	Lan Ha	94	0	446	93.5%
Orchid Trendy	Lan Ha	70	0	544	96.7%

Ambassador Signature’s count is recent: 93 of its 97 August reviews went up in August 2026. A parent posting on 8 August 2026 took three children, aged 15, 13 and 10, on the two-day trip, found the ride smooth, and liked the shuttle but suggests comparing its price.

Sixty-three of Nostalgia’s August reviews went up in August 2025, six of them in the last eleven days. A family posting on 7 August 2025 had connecting rooms, kayaked and swam, and their 11-year-old liked the water slide best. Two Orchid Trendy guests who sailed for two nights on 8 and 9 August 2025 found the trip well organised and noted reasonable drink prices and happy hours.

What should you ask before booking an August cruise?

Ask these four, by email, before you pay.

1. If the authorities stop licensing boats on my date, do I get a refund or a new date, and how soon will you tell me?
2. If the closure comes after I have left Hanoi, who pays for the transfer back?
3. If a two-night trip loses a night, what comes back?
4. Is 2 September in your holiday window for 2027, and what is the surcharge for each adult and each child?

The month by month comparison sets August against the other eleven months.

August cruise questions

Is August a good month for a Ha Long Bay cruise? In our view, yes, if your plans can bend around a storm. August is the wettest month on Ha Long Bay, at 456 mm, with a sea of 31.7°C and eight hours of sun a day. Of the 1,469 August reviews counted on 28 October 2026, 4.5% give one or two stars, level with the 4.5% average for all months.

Will my August cruise be cancelled? Only if a storm reaches the bay, and then the province decides when boats stop. In 2026 sightseeing and overnight licences stopped from 07:00 on 22 August for storm no. 4. Cancellations come up in more August reviews than in any other month, 10 of 1,469, and at least five describe trips called off for weather in late August 2025. Get the operator’s closure terms in writing before you pay.

What should I pack for August? Expect to get wet on an August cruise on Ha Long Bay: rain falls on about 25 days of the month, so a light rain jacket earns its space. Days average 30.6°C and nights 26.7°C, and the warmest August day in ten years reached 35.6°C, so bring sun protection and thin clothes. The sea averages 31.7°C, warm enough to swim from the boat.