Ha Long Bay weather in short
The bay has a clear split. From about November to March it is cooler and drier. From May to September it is hot and humid, with the heaviest rain in July and August. Storms are most likely in the summer months.
The figures below are long-term monthly averages for the Bai Chay weather station on the coast of Ha Long City. They come from a Vietnamese climate standard for buildings published in 2022, so they describe the typical pattern, not the forecast for your dates. Conditions on the water can differ from the shore.
Monthly climate at Bai Chay
Average daily highs and lows and average monthly rainfall. These are means, not records.
| Month | Average high °F (°C) | Average low °F (°C) | Rain in (mm) |
|---|---|---|---|
| January | 67 (19.3) | 57 (14.0) | 1.1 (27.7) |
| February | 67 (19.7) | 59 (15.2) | 1.0 (24.5) |
| March | 72 (22.0) | 64 (17.8) | 1.7 (42.9) |
| April | 79 (26.1) | 71 (21.5) | 3.4 (86.3) |
| May | 86 (30.1) | 76 (24.6) | 7.2 (183.2) |
| June | 89 (31.5) | 79 (26.0) | 11.7 (297.0) |
| July | 89 (31.7) | 79 (26.2) | 14.3 (364.3) |
| August | 88 (31.3) | 78 (25.4) | 16.9 (430.5) |
| September | 87 (30.7) | 76 (24.4) | 10.9 (276.0) |
| October | 84 (28.8) | 72 (22.2) | 5.6 (142.6) |
| November | 78 (25.5) | 66 (18.7) | 1.5 (38.9) |
| December | 71 (21.7) | 60 (15.3) | 0.7 (18.1) |
Fog is part of the winter picture. The same station averages 1.3 foggy days in January, 2.5 in February and 4.2 in March, so a cool season does not always mean clear views.
Cruises and tours in the bay
Day trips and overnight cruises, with live prices and availability.
What each season means for a visit
Our reading of the averages above. It is a judgment, not a promise.
December to February: cool and dry
Little rain, but average lows of 57 to 60 °F (14 to 15 °C) and some fog. Bring a layer for the deck and for evenings on board. Swimming is less appealing.
March and April: warming up
Highs rise from 72 to 79 °F (22 to 26 °C) and rain increases from April. March has the most fog days of the winter months.
May to September: hot and wet
Highs reach 86 to 89 °F (30 to 32 °C) and rain peaks in July and August. This is also the storm season, so build slack into your plans.
October and November: easing off
Rainfall drops from 5.6 in (142.6 mm) in October to 1.5 in (38.9 mm) in November, and highs fall from 84 to 78 °F (29 to 26 °C). Nationally, the storm season can last until November.
Best time to visit Ha Long Bay
On the numbers alone, November and April are the balanced choices. November combines low rain with highs near 78 °F (26 °C), and April is warm with moderate rain. December to February suits you if you want the least rain and do not mind cool evenings and some fog. The hottest, wettest weeks fall from June to September.
No month is storm-free, and no source guarantees a good week. Book flexible dates if you can, and ask your operator how it handles weather changes before you pay.
Storms and suspensions
The 2022 climate standard names June to September as the main storm period for the Quang Ninh and Thanh Hoa coast, and June to November for Vietnam as a whole. The practical effect is that boats stop. Press reported that from 7 am on 22 August 2026 departures and overnight stays in Ha Long and Lan Ha were suspended because of storm number 4, until the final storm bulletin. A booked ticket or a booked ship does not lift such a suspension.
If a storm is forecast, expect your operator to change or cancel the trip. Check the forecast for the days before you leave, and keep a spare night in Hanoi or Ha Long City at the end of the trip. For travel from Hanoi, see the Hanoi guide. For cruise types and what is included, see our cruise comparison.
Planning to continue south? Lan Ha Bay and Cat Ba have their own pages at VisitCatBa, and Hoi An has a separate weather page for central Vietnam.
Ha Long Bay weather: frequently asked questions
What is the best month to visit Ha Long Bay?
November and April balance rain and temperature best on the monthly averages. December to February is the driest, but cooler and sometimes foggy. No month is guaranteed.
When is the rainy season?
Rain peaks from June to September. August averages 16.9 in (430.5 mm) and July 14.3 in (364.3 mm) at Bai Chay.
When are typhoons most likely?
A 2022 climate standard names June to September as the main storm period for the Quang Ninh coast and June to November for the country. Departures can be suspended at short notice.
How cold does it get in winter?
Average lows are 57 °F (14.0 °C) in January and 59 °F (15.2 °C) in February, with highs near 67 °F (19 to 20 °C). It feels cooler on deck and at night.
Is there fog in the bay?
Yes, mostly in late winter. The station averages 1.3 foggy days in January, 2.5 in February and 4.2 in March.
Can I swim in the bay?
Swimming depends on the stop, the program and the conditions on the day. Water temperatures are not covered by these figures, so ask your operator.