Lan Ha Bay Weather: Month by Month, and When the Boats Stop

Lan Ha Bay can be cruised in any month, but each season costs something. From June to September it is hot and wet, the water is warm for swimming, and it is the storm season: Vietnam’s national climate standard says storms reach the coast from Quang Ninh to Thanh Hoa mostly in those months, and in 2026 storms closed the sea around the bay twice. December to February are cool and dry, and February to April damp, grey and misty, with the most fog in March. October, November, April and May sit between. No sea ban was in force on 1 November 2026. A cruise that lets the captain choose the stop for the weather, like BAT Group’s Hanoi: 2 Days Lan Ha & Halong Bay 5-Star Cruise with Balcony, from $142 in current promotion (usually $182) a person (checked November 2026), copes best.

The calendar above is that cruise: check-in at Tuan Chau Harbor, then either the Dark and Bright Cave by kayak or bamboo boat or a swim at Ba Trai Dao or Tra Bau, chosen by the captain on the day for the weather and the tide, a night at anchor, and a kayak or a cave on Cat Ba the next morning.

Month by month

Long-term means for Bai Chay in Ha Long, the nearest station in the tables (there is none on Cat Ba), from Vietnam’s climate standard for construction, QCVN 02:2022/BXD (Ministry of Construction, with data from the national meteorology institute up to 2017). Rounded.

The sunniest months by the same tables are July (about 187 hours of sun), then September, October and May, each around 177 hours. The dullest are March (about 43 hours) and February (48): late winter and early spring bring what the standard calls nồm, damp weather with relative humidity above 95 per cent, drizzle and sea fog. Fog spoils the view of the karst more than it stops the boats; no authority says fog alone holds cruises in port.

Storms and sea bans

When a storm or tropical depression heads for the Gulf of Tonkin, Hai Phong’s civil defence command and Quang Ninh’s authorities stop issuing departure permits from a set hour, and lift the ban once the national forecasting centre issues its final bulletin on the storm. In 2026 that happened twice:

Hai Phong civil defence command, the Ha Long Bay board’s notice and the Hai Phong city press, July and August 2026. The date Ha Long reopened after Narra was not found in the published notices.

Storm Narra reached the sea off Quang Ninh and Hai Phong on 22 August; more than 1,700 visitors were on Cat Ba, nearly 300 of them foreign, and the car ferry stayed shut until it ran again. No storm or tropical depression entered the East Sea in October 2026, and the national forecasting centre’s outlook for November 2026 expected fewer than the long-term average of 1.5 a month.

Outside storms, the rule is the sea itself. Hai Phong’s instruction for tourist boats of August 2026 (document 10736/VP-XDCT) tells ports not to let tourist boats leave in adverse weather, and sets the wave limits at 1.3 m for VR-SI boats and 1.85 m for VR-SB. The cruise listings on this site say their itineraries can change at short notice for the weather or the tide.

What happens to your booking

If the port authorities hold the boats, the cruise does not sail. Taliya's day cruise, for example, says a cruise cancelled for major weather is refunded in full; the others say the itinerary may change for weather and tide. Check the cancellation terms on the listing you book, and in July to September keep a spare day in your plans after the cruise rather than before a flight.

The best months

• October and November: warm (about 22 to 25 °C on average), the rain falling away, lots of sun and almost no fog. Storms are still possible early in the period.
• April and May: warming up, more sun than winter, the rain and thunder starting to build in May.
• December and January: dry and cool, around 16 to 18 °C; cool for swimming, fine for kayaking in a light jacket.
• February and March: the greyest months, with drizzle and the most fog.
• June to September: the warmest water and the long days, with the wettest weather and the storm season.

Pick your cruise

Prices, ratings and review counts from the listings (GetYourGuide checked November 2026). Operators price by date and season, so treat the figures as the shape of the market, not a quote.