Planning

When not to go

Every month is good somewhere in the region, and every month is bad somewhere. This page collects the times and places where the risk is high enough that we would change the plan: smoke in the north, storms and floods on the Vietnamese coast, heat in April, and the holidays when the country closes.

By Tourist Bucket editors · Published 2026-10-26 · Last reviewed 2026-10-26 · Corrections

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The short version

Risk	Where	When	Source
Smoke haze	Northern Thailand (Chiang Mai) and northern Laos	December to April; worst about February to March	Climate and health sources, UK advice
Typhoons	Vietnam's east coast	Normally May to November	UK Foreign Office
Floods	Central Vietnam (Hue, Hoi An)	October and November; risk from September	UK Foreign Office; Vietnam tourism authority
Storms at sea	Ha Long Bay; Phu Quoc	June to August; July to September	Vietnam tourism authority
Extreme heat	Angkor, Luang Prabang, Chiang Mai	April, with March and May close behind	Climate tables
Holiday closures	Vietnam at Tet; Thailand, Laos and Cambodia in mid-April	February 2027; April each year	Government notices
Conflict	Myanmar; Cambodia–Thailand border zone	Current	UK Foreign Office

Sources: Wikipedia — Chiang Mai (climate and festivals); Wikipedia — Air pollution in Thailand; UK Foreign Office — Thailand health; UK Foreign Office — Vietnam safety and security; Vietnam National Authority of Tourism — weather and climate; Wikipedia — Siem Reap climate table; Ha Tinh provincial portal — Tet 2027 holiday (Ministry of Home Affairs notice); UK Foreign Office — Myanmar travel advice; UK Foreign Office — Cambodia travel advice · last checked 2026-10-26.

The smoke season in northern Thailand and Laos

Agricultural and forest burning fills the northern valleys with smoke each dry season. In Chiang Mai, pollution occurs mainly between December and April, with March often singled out as the worst month; recorded peaks include PM2.5 of 183 µg/m³ in 2018 against a WHO guideline of 25. Studies of the north describe the haze peaking from about January to March, worst in February and March.

The UK Foreign Office warns that pollution in Chiang Mai can reach dangerous levels and worsen bronchial, sinus or asthma conditions, and recommends checking the World Air Quality Index. For Laos it notes that regional air pollution can aggravate heart, lung or respiratory conditions. Views from mountain viewpoints disappear and outdoor activity becomes unpleasant.

Our view: if you have a respiratory or heart condition, or are travelling with small children, avoid Chiang Mai and the north of Laos from late February to early April. Others should check the air quality index daily and keep the south of either country as a fallback.

Sources: Wikipedia — Chiang Mai (climate and festivals); Wikipedia — Air pollution in Thailand; UK Foreign Office — Thailand health; UK Foreign Office — Laos health · last checked 2026-10-26.

Typhoons and floods in Vietnam

The typhoon season normally runs from May to November along Vietnam's east coast, bringing strong winds, heavy rain, flooding and transport disruption, and storms can occur at other times. The rainy season is June to September in the north and south, and October to December in the centre. Seasonal flooding occurs in October and November in central Vietnam, and flooding is also common around Hanoi along the Red River and in the Mekong Delta. During floods, roads can be blocked by landslides and mudslides.

The national tourism authority places Hue's flood risk from September to November and describes Hoi An as rainy from September to January. For a traveller that means: avoid fixed, non-refundable plans on the central coast in October and November; on Ha Long Bay, expect cruise cancellations when storm warnings are issued, especially from June to August; and keep a spare day on any mountain drive in the rains.

Sources: UK Foreign Office — Vietnam safety and security; Vietnam National Authority of Tourism — weather and climate · last checked 2026-10-26.

Heat

April is the hottest month in the three Mekong destinations most visited: average daily maxima are about 35.8 °C in Siem Reap, 35.2 °C in Luang Prabang and around 36.7 °C in Chiang Mai, with records above 41 °C. The UK Foreign Office notes that heat and humidity can be severe in Vietnam, particularly in the rainy season, and that dehydration and heatstroke can be fatal. Temple sites have little shade.

If April is your only option, go to the temples at first light, rest from late morning to mid-afternoon, and carry more water than seems necessary.

Sources: Wikipedia — Siem Reap climate table; Wikipedia — Luang Prabang climate table; Wikipedia — Chiang Mai (climate and festivals); UK Foreign Office — Vietnam safety and security · last checked 2026-10-26.

Holidays when the country closes

Tet in Vietnam. The 2027 holiday for public employees is 4 to 10 February 2027, around Tet on 6 February. Transport before and after is full, and many small businesses close in the first days of the year.

The April new year. Thailand's Songkran (13 to 15 April) and the Lao and Cambodian new year holidays (14 to 16 April in 2026) close offices and banks, slow the roads and soak anyone outdoors in the busiest streets.

Cambodia's other three-day holidays. Pchum Ben (10 to 12 October 2026) and the Water Festival (23 to 25 November 2026) send many people to their home provinces or to Phnom Penh.

Buddhist holy days at Angkor. The upper level of Angkor Wat is reported to close on Buddhist holy days.

Sources: Ha Tinh provincial portal — Tet 2027 holiday (Ministry of Home Affairs notice); Thairath — April 2026 public holidays; Vientiane Times — 2026 public holidays (Prime Minister's Office); Andersen Cambodia — Sub-Decree 167 on 2026 public holidays (law firm summary); Adventures Cambodia — Angkor temple opening hours (tour company blog) · last checked 2026-10-26.

Advisories and closed areas

Myanmar. The UK Foreign Office advises against all but essential travel to large parts of the country, including Mandalay Region where Bagan lies, and against all travel to others; it warns that the situation may deteriorate at short notice.

Cambodia–Thailand border. The same office advises against all but essential travel within 20 km of Cambodia's land border with Thailand. Land border crossings are suspended and several border temples, including Preah Vihear, are closed; landmines and unexploded ordnance are present in the area.

Southern Thailand. UK advice is against all but essential travel to the four southern provinces bordering Malaysia.

Sources: UK Foreign Office — Myanmar travel advice; UK Foreign Office — Cambodia travel advice; UK Foreign Office — Thailand safety and security · last checked 2026-10-26.

A different month, or a different place

Smoke in Chiang Mai in March: central Vietnam is dry from February, and Angkor is dry until April.
Floods on the central Vietnamese coast in October and November: northern Vietnam is cool and dry, buckwheat is in flower, and Angkor's dry season is starting.
Storms on Ha Long Bay in summer: the central coast is dry and hot until August.
April heat at Angkor: consider November to February instead, accepting the crowds.

Common questions

Questions readers ask

When is the haze season in Chiang Mai?

Pollution occurs mainly from December to April, with February and March usually the worst months.

When is typhoon season in Vietnam?

Normally from May to November along the east coast, according to the UK Foreign Office, though storms can occur at other times.

When does central Vietnam flood?

Seasonal flooding occurs in October and November, with risk from September, in Hue, Hoi An and the surrounding provinces.

Which month is hottest at Angkor?

April, with an average daily maximum of about 36 °C in Siem Reap.

Lion dancers and motorbike riders fill a Hanoi street decorated with red Tet banners and lanterns.

Calendar · First quarter

January to March

Tet, Angkor in its driest months, the cold north of Vietnam and the smoke season: what January to March holds.

A local woman herds a buffalo and calf past blooming plum trees on the Dong Van karst plateau in Ha Giang.

Calendar · Fourth quarter

October to December

Buckwheat blossom, Loi Krathong and Yi Peng, Bon Om Touk, Angkor's new dry season and the central coast floods.

Golden naga serpent statues flank the illuminated entrance staircase of a Buddhist temple in Chiang Mai at night.

Planning

Planning around a date

How to plan around an official, announced or calculated date: booking windows, price spikes and spare days.

Ancient brick temples rise above a green plain in Bagan, Myanmar, seen from above at dawn.

Seasons · Myanmar

Bagan balloon season

What we could and could not confirm about balloon flights over Bagan, sunrise times and the UK travel advice.

Silhouette of Angkor Wat's towers and palm trees reflected in a still pool at dawn in Siem Reap

Seasons · Cambodia

Angkor sunrise season

Sunrise times by month at Angkor Wat, the official pass prices and hours, the sunrise temples and the Bakheng cap.

The Japanese Covered Bridge in Hoi An glows purple at night, reflected in the river with floating lanterns below.

Festivals · Vietnam

Hoi An lantern nights

Every Hoi An lantern night through 2027, with the lights-off time, the old town ticket and the flood months.

Start planning

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