Ha Long Bay in April: warm sea, holiday crowds

April is the month Ha Long Bay turns warm enough to swim without flinching. Ten years of modelled weather give days of 26.5°C and nights of 22.2°C, the sea reaches 25.7°C, and the sun shows for 8.2 hours a day against 5.7 in March. More reviews are posted in April than in any other month. The catch comes at the end: from Friday 30 April to Monday 3 May 2027 Vietnam takes a four-day national holiday, and some boats add a surcharge for those nights.

Review figures come from the 1,123 reviews posted in April, of 10,058 dated reviews for 74 boats counted on 16 October 2026. 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 April?

Warm and mostly bright, with most of the rain after the 10th. These are April averages for 2016 to 2025 from ERA5 reanalysis, a model grid about 25 km wide that smooths out the extremes.

April, 2016–2025	Average
Daytime high	26.5°C
Night-time low	22.2°C
Coldest night in the ten years	15.4°C (2 April 2025)
Warmest day in the ten years	35.1°C (30 April 2024)
Days with any rain (0.1 mm or more)	17.7
Days with 1 mm of rain or more	9.9
Rain in the month	68 mm (46 mm in the driest year, 104 mm in the wettest)
Relative humidity	85%
Sunshine	8.2 hours a day
Sea-surface temperature	25.7°C (three Aprils)

Over the decade the first ten days averaged 7 mm a year, the middle ten 28 mm and the last ten 33 mm, while daytime highs climbed from 25.2°C to 27.5°C. The air stays damp: April’s humidity of 85% is the third highest of the year, behind March and August.

Mist can still turn up in April. A guest on Orchid Trendy, posting on 11 April 2025, found it foggy at 24°C and called the trip mystic. Two days later a family on Capella called the cruise the high point of their Vietnam trip: the weather was dull, the view through the mist spectacular, and the kitchen went to real lengths for a vegetarian wife. Those are the only two April text reviews that mention fog or mist.

Can you swim in April, and how rough does it get?

Yes, for most people. The sea averaged 25.7°C over three Aprils, from 21.1°C on the coolest day to 30.1°C on the warmest, nearly five degrees up on Ha Long Bay in March. An Ambassador Signature guest posting on 25 April 2026 used the boat’s slide to get into the water and swam.

The wind is the part that changes. Gusts of 50 km/h or more came on 33 April days in ten years, 3.3 a year, against 2.0 in March. Two of the decade’s 50 gustiest days fell in April: 16 April 2022, at 69.5 km/h, which was also the wettest April day with 64 mm of rain, and 30 April 2024, at 67.3 km/h, the same day the model’s April high peaked at 35.1°C. Waves stay modest, with the day’s highest averaging 0.39 m on open water over four Aprils. Our weather guide explains who decides whether boats sail.

When are the April holidays in 2027, and how busy do they get?

There are two. Hung Kings’ day, the tenth day of the third lunar month, falls on Friday 16 April 2027, which makes a long weekend to Sunday 18 April. Reunification Day and Labour Day fall on Friday 30 April and Saturday 1 May, and under Vietnam’s Labour Code the Saturday holiday earns a day off on Monday 3 May, so the break runs four days, as reported by Tuổi Trẻ on 11 October 2026 and, as a union proposal, by Thanh Niên on 12 August 2026.

The week of 30 April to 3 May is the crowded one. Over the four days from 30 April to 3 May 2026, Báo Quảng Ninh reported about 910,000 visitors to the province, 873,000 of them Vietnamese, and about 70,300 visits to Ha Long Bay itself. A year earlier, on 29 April 2025, Tuổi Trẻ reported that many cruise boats on the bay could take no more guests for the holiday, and Paradise, a cruise operator, told the paper its Vietnamese bookings for that holiday were up 15% on the year before.

One guest’s honeymoon cruise was changed by the weather. Posting on 29 April 2026, they say an incoming storm meant the boat could not get a permit to sail, and everyone was moved to a different boat, with a smaller room, after about two hours on board. Had they known, they would have chosen to cancel. In ten years of model data, 20 of the 40 days from 30 April to 3 May had a millimetre of rain or more, though only four reached 10 mm; four of the 40 had gusts of 50 km/h or more, three of them from 30 April to 2 May 2024.

April’s lead in reviews posted, 1,123, tracks guest numbers only loosely. Crowd words turn up in 33 of the 1,010 April text reviews, 3.3%, against 2.9% across the year, a gap small enough to be chance. An Alisa Premier family posting on 8 April 2025 waited an hour to get into Sung Sot, the Surprise Cave, and thought the cave worth it.

How much do boats charge for 30 April and 1 May?

Two operators we list publish a figure on their own sites, read on 16 October 2026: $25 a person on one boat, about $8 on the other. Aqua of the Seas charges $25 a person for 30 April, on the page carrying its rates from 1 October 2026 to 30 April 2027; 1 May is not in that line. Cozy Bay Grand lists 200,000 dong, about $8, a person for 30 April and 1 May, and again for 2 September, in its 2026 price guide.

For any other boat, ask for the 2027 figure in writing, and check whether the window covers 2 and 3 May as well as 30 April and 1 May.

Are April reviews better or worse than average?

About average overall, with a weak last ten days, about half of those low scores from 2025. As posted, 52 of the 1,123 April reviews (4.6%) sit at one or two stars, against 520 of 10,058 (5.2%) across all months, a gap small enough to be chance.

April, posted on	Reviews	One or two stars
1 to 10 April	470	16 (3.4%)
11 to 20 April	333	11 (3.3%)
21 to 30 April	320	25 (7.8%)

The last ten days carry about half the month’s low scores in under a third of its reviews, more than chance would explain. Most of that is 2025: 13 low scores in 117 reviews posted from 21 to 30 April 2025, spread over eight boats. The same ten days in 2026 had 5 in 136.

Of the 42 low April reviews we have classified, 28 mention the food (66.7%, against 199 of 353, 56.4%, for low reviews in all months) and 20 the cabin (47.6% against 37.4%). Forty-two is a small sample, and neither difference is large enough to rely on.

Two low reviews from early April 2026 describe paying for breakages: $19 for a wine glass a four-year-old broke, and a charge for a mug the guests say fell with the boat’s movement while they slept.

Which boats did well in April?

Stellar of the Seas, Alisa Premier and Ambassador Signature had the most April reviews without a single one or two star score, among boats with 100 or more reviews collected over at least a year, counted on 16 October 2026.

Boat	April reviews	One or two stars in April	All reviews	Five stars, all reviews
Stellar of the Seas	73	0	499	99.4%
Alisa Premier	56	0	393	92.1%
Ambassador Signature	41	0	379	95.8%

Ambassador Signature’s 41 April reviews are thin for one month, so read them alongside its 379 overall. A vegetarian Indian guest on that boat, posting on 20 April 2026, had worried about food and found Indian menus at every meal. A Stellar of the Seas guest posting on 14 April 2025 got rain, sunshine and cloud and liked all of it.

What should you ask before booking an April cruise?

Four questions, by email, so the answers are in writing.

1. Does my night fall in your holiday window for 2027, and what is the surcharge in dollars for each adult and each child? Ask about 16 April as well as 30 April to 3 May.
2. If the port does not let boats sail, do I get a different boat, a new date or my money back, and will you tell me before I travel?
3. What do you charge if something gets broken in the cabin or at the table?
4. If I am travelling over the holiday, what time does the shuttle leave Hanoi, and how long should I allow for the road?

Our Hanoi to Ha Long guide covers the drive, and the cancellation policy guide shows how much the ordinary terms differ.

April cruise questions

Is April a good month for a Ha Long Bay cruise? In our view it is one of the better ones: days of 26.5°C, a sea of 25.7°C and 8.2 hours of sun. Of the 1,123 April reviews counted on 16 October 2026, 4.6% give one or two stars, close to the 5.2% average across all months. Avoid 30 April to 3 May 2027 if you want fewer people and no surcharge. The month by month comparison sets April against the rest.

When is the 30 April holiday in 2027? Reunification Day falls on Friday 30 April 2027 and Labour Day on Saturday 1 May. Under the Labour Code the Saturday earns a day off on Monday 3 May, so the break runs four days. Hung Kings’ day falls earlier, on Friday 16 April, and makes a separate long weekend to Sunday 18 April. Some boats charge extra over the holiday: Aqua of the Seas, for example, adds $25 a person for 30 April. The dates are as reported by Tuổi Trẻ on 11 October 2026.

Is the water warm enough to swim in April? For most people, yes. The sea averaged 25.7°C over three Aprils, from 21.1°C on the coolest day to 30.1°C on the warmest, against 21.0°C in March. Waves stay modest, with the day’s highest averaging 0.39 m, though gusts of 50 km/h or more come on about three April days a year. Ha Long Bay in May is warmer again, at 29.3°C.