Hoi An weather by month, the rainy season and Thu Bon river floods
The driest months in Hoi An are February to April; October and November are the wettest, when the Thu Bon river rises and floods the old town. In October 2025 it reached about 3.4 m, close to the 1964 record. Beach weather runs from May to July.
October and November are the wettest months in Hoi An: the QCVN 02:2022/BXD norm for Da Nang is 628 mm of rain in October and 448 mm in November, with rain on about 20 days a month. That is also when the Thu Bon river overflows and floods the old town: in October 2025 it rose to about 3.4 m, close to the 1964 record. The driest months are February to April. The beaches at An Bang and Cua Dai are most comfortable from May to July.
Hoi An is now part of Da Nang city, so the data is taken from the Da Nang station, the nearest one in the norm; it is about 30 km from the old town, so the weather on a given day can differ.
What is the weather in Hoi An by month?
The closest station to Hoi An in the tables of QCVN 02:2022/BXD (Ministry of Construction, Appendix A: tables A.2, A.25, A.28) is Da Nang. These are long-term averages used by builders, not a forecast for your dates. We do not use the Tam Ky station, which is also in the norm: it is further south and much wetter (2,749 mm a year against 2,205 mm for Da Nang).
| Month | Mean temperature, °C | Rainfall, mm | Rainy days | What it means |
|---|---|---|---|---|
| January | 21.5 | 81.9 | 12.0 | cool, drizzly |
| February | 22.4 | 23.6 | 5.6 | driest month |
| March | 24.2 | 25.0 | 4.8 | dry and warm |
| April | 26.5 | 35.3 | 5.4 | dry, getting hot |
| May | 28.4 | 81.1 | 9.2 | hot, rain is rare |
| June | 29.4 | 82.6 | 8.1 | hot, drier |
| July | 29.3 | 92.5 | 9.4 | hot, drier |
| August | 29.0 | 141.2 | 11.6 | hot, more rain |
| September | 27.6 | 350.7 | 14.6 | rainy season starts |
| October | 26.0 | 628.0 | 20.0 | wettest, flood risk |
| November | 24.4 | 448.2 | 20.3 | rain and floods |
| December | 22.2 | 218.4 | 18.7 | cool, still rainy |
For the year: 25.9 °C on average, 2,205 mm of rain and 139 rainy days. The monthly mean never drops below 21.5 °C (January) or rises above 29.4 °C (June).
When is the rainy season in Hoi An?
The rainy season in Hoi An runs from September to December and peaks in October and November. The QCVN norm gives 351 mm for September, 628 mm for October, 448 mm for November and 218 mm for December. Vietnamtourism (updated 14 September 2026) puts the wet season at September to January and calls October and November the wettest. The typhoon season officially lasts from June to November, with the highest risk in September to November. Airports close in storms: on 11 October 2020 storm No. 6 stopped Da Nang and Chu Lai for a few hours (Tuổi Trẻ).
Does Hoi An flood, and when?
Yes, almost every autumn. The old town stands on the lower Thu Bon, and after heavy rain the Hoai river floods the embankment and the nearest streets. The strongest flood came in October 2025: the Thu Bon at Hoi An reached 3.37 m on 30 October (Tuổi Trẻ, 30 October 2025), about the level of the historic 1964 flood at 3.40 m. The government portal forecast about 3.5 m on 29 October 2025. By the morning of 31 October the water was down to 0.13 m above the third alarm level (VnExpress, 31 October 2025). Newspapers write "above the 1964 record" or "just below": their figures differ by centimetres, so trust the official bulletins.
What happened in the old town in October-November 2025?
The old town was cut off and water stood 2-3 m deep in many shops; Thanh Ha pottery village, with about 400 households, was isolated for four days and tourist activity stopped (VnExpress, 31 October 2025). The Anantara resort moved guests out from 28 October. By 17 November 2025 the old town had flooded for the third time since late October: water reached the foot of the Japanese Covered Bridge, the town was still full of tourists, and some visitors rented boats on the Hoai (Tuổi Trẻ, 17 November 2025). Earlier, on 15 November 2023, the Thu Bon rose to 1.77 m and flooded Bạch Đằng and Nguyễn Thái Học streets and the pedestrian street (government portal). The water usually goes down within a day or two (Hoi An heritage centre, 16 November 2020).
How do I follow warnings and what should a tourist do?
Watch the flood bulletins on the national forecast site nchmf.gov.vn (they are also posted on kttv.gov.vn); flash floods and landslides have a separate site, luquetsatlo.nchmf.gov.vn. If the forecast shows a flood above the second alarm level at Hoi An, hotels usually warn guests themselves. Move your suitcase and documents to an upper floor, do not leave things on the ground floor, and ask the hotel beforehand about evacuation and food. Do not ride a motorbike through floodwater: engines and brakes suffer, and hidden holes are invisible; agree with the rental company how to return the bike, see transport rental. Before a flight, check it with the airline: Da Nang closes during storms and this is announced on the day. For travel between cities, see our guide on getting to Hoi An. A working local SIM helps you receive warnings and keep maps: see mobile and SIM.
Can I take a boat through the flooded old town?
In a flooded old town boats carry residents and relief supplies: on 30 October 2025 boats were moored on Trần Hưng Đạo street (Tuổi Trẻ). When the water reached the foot of the Japanese Covered Bridge on 17 November, some tourists took boats themselves (Tuổi Trẻ). This is not a regular route with a timetable: boats appear while the water stays, and the risk is yours. Residents feel differently about it, so photograph with respect and do not get in the way of the clean-up.
When can I swim at An Bang and Cua Dai?
It is most comfortable from May to July: Vietnamtourism says An Bang and Cua Dai are at their peak in May to July and recommends June and July for a beach holiday. From October to December there is rain, storms and surf, so skip swimming on stormy days. February to April is dry and suits walks around town, but water temperature is not part of the QCVN data. The coast from An Bang to Cua Dai was eroded: after a submerged breakwater was finished in 2024 the sand came back, and a stretch of about 2.3 km between the Victoria resort and Thịnh Mỹ has wide, fine sand (VnExpress, 12 April 2025). Another 5.2 km of shore is being protected under a project launched on 20 March 2025 and planned to finish in 2026, so there may be works on some stretches; check before you go.
When is the lantern festival in Hoi An?
The full-moon festival is held on the night of the 14th day of every lunar month, from 18:00 to 22:00. The old houses and shops switch off electric light, traffic is kept out, lanterns are hung and floating lanterns are released on the Hoai river (Mia.vn, 5 August 2026). The dates on the Gregorian calendar change every year: look up the 14th day of the lunar month in a lunar calendar. We do not give specific dates without a source. Arrive early and wear comfortable shoes, because vehicles do not run at that hour. What to see in the old town by day is in the Hoi An sights section.
Frequently asked questions
When is the rainy season in Hoi An? September to December, peaking in October and November: 628 and 448 mm of rain a month by the norm.
Which months are the driest? February to April: 24 to 35 mm of rain and 5-6 rainy days a month.
How hot does it get in summer? The mean temperatures of June and July are 29.4 and 29.3 °C.
Does it flood every year? Floods in the old town recur in autumn; in 2023 the river reached 1.77 m, in 2025 about 3.4 m.
What is the third alarm level? It is an official step in the river flood warning: exceeding the third level means a dangerous flood. Follow the bulletins on nchmf.gov.vn.
How long does the water stay in the old town? Usually a day or two (Hoi An heritage centre, 2020), but in November 2025 the old town flooded several times in a month.
When can I swim at An Bang and Cua Dai? Most often from May to July. Stay out of the water in storms and in November-December.
When is the lantern festival? On the night of the 14th day of the lunar month, from 18:00 to 22:00. Check the date for the month in a lunar calendar.
Is Hoi An still in Quang Nam? No: since 1 July 2025 it is part of Da Nang city (the wards Hội An, Hội An Đông and Hội An Tây).
Sources and checking
Weather: QCVN 02:2022/BXD (Ministry of Construction, 26 September 2022), tables A.2, A.25, A.28, Da Nang station. Season: Vietnamtourism (14 September 2026). Floods: government portal (29 October 2025, 15 November 2023), Tuổi Trẻ (30 October 2025, 17 November 2025), VnExpress (31 October 2025), Hoi An heritage centre (16 November 2020). Bulletins: nchmf.gov.vn, kttv.gov.vn, luquetsatlo.nchmf.gov.vn. Beaches: VnExpress (12 April 2025). Lantern festival: Mia.vn (5 August 2026). Airports in storms: Tuổi Trẻ (11 October 2020). Administrative division: Resolution 1659/NQ-UBTVQH15. We do not publish prices. Updated 23 October 2026.