A dated calendar of Southeast Asia travel experiences
Calendar · Second quarter
April to June: water festivals, fireflies, first rains
April is the hottest month across most of the region and the one in which Thailand, Laos and Cambodia all celebrate their new year within a few days of each other. By May the rains have started in the south and the forests of northern Vietnam fill with fireflies and butterflies.
The quarter at a glance
| Month | What is on | What to watch |
|---|---|---|
| April | Songkran 13–15 April; Pi Mai Lao and Khmer New Year 14–16 April (2026 dates); lantern night 20 April 2027 | Hottest month at Angkor and in Luang Prabang; smoke lingers in the north |
| May | Cuc Phuong fireflies late April to early May; butterfly season begins; lantern night 19 May 2027 | Rains begin in Cambodia, southern Vietnam and Laos |
| June | Lantern night 18 June 2027; central Vietnam dry and hot | Rain and storms start in the north of Vietnam |
Sources: 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); VietnamPlus — fireflies in Cuc Phuong National Park; Tourist Bucket lunar and sun calculations (PyEphem, UTC+7), cross-checked with a Chinese-calendar library · last checked .
Three new years in one week
Thailand's Songkran holiday runs from 13 to 15 April; in 2026 the government holidays, with a weekend, gave a five-day break from 11 to 15 April. Laos announced Pi Mai Lao as 14 to 16 April 2026, and Cambodia's holiday sub-decree set Khmer New Year for the same three days. The 2027 dates will be published by each government; they are expected in the same mid-April window.
All three involve water, temples and family visits. In cities with large visitor numbers the water throwing is street-wide and lasts for days. Anything you carry outdoors can get wet, including phones and passports. Transport is busy before the holiday and quiet during it, and many offices and some shops close.
The April new year page compares the three in detail.
Sources: 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); Wikipedia — Chiang Mai (climate and festivals) · last checked .
The heat
April has the highest average daily maximum of the year in Siem Reap, about 35.8 °C, and in Luang Prabang, about 35.2 °C. Chiang Mai's April average maximum is around 36.7 °C. Temple visits are comfortable only in the first hours after sunrise and the last hour before sunset; the middle of the day is for shade.
The heat and the smoke overlap in northern Thailand and Laos in the first half of April. Rain usually begins to clear the air in May.
Sources: Wikipedia — Siem Reap climate table; Wikipedia — Luang Prabang climate table; Wikipedia — Chiang Mai (climate and festivals) · last checked .
Fireflies and butterflies in Cuc Phuong
Cuc Phuong National Park, in Ninh Binh province and more than 100 km from Hanoi, has a firefly season from late April to early May each year, visible in the forest in the evening. Since May 2024 the park has run evening tours from 19:00 to 22:00 by electric car along a 5 km route, with around 100 visitors a session; reported prices at launch were VND 100,000 for adults and VND 50,000 for children.
The butterfly season follows, typically late April to June and peaking around the 30 April and 1 May holidays. In 2026 butterflies appeared two to three weeks early, in early April. Those holidays are also the busiest days in the park, with tens of thousands of visitors on peak days.
Fireflies and butterflies are both weather-dependent; a cold or dry spring shifts the season. The nature seasons page has more detail.
Sources: VietnamPlus — fireflies in Cuc Phuong National Park; VTV — Cuc Phuong night tour; Dan Tri International — 2026 butterfly season in Cuc Phuong · last checked .
The first rains
The wet season starts in May in Siem Reap, southern Vietnam and Laos. Siem Reap averages about 150 mm in May and 214 mm in June, and the national tourism authority describes the south of Vietnam as wet from May to November with brief afternoon downpours. Northern Vietnam turns hot and stormy from June; Hanoi highs can approach 40 °C in June.
Central Vietnam is the exception. Hoi An is dry and sunny from February to August and Hue from March to August, which makes the central coast the most dependable beach and lantern-night destination of this quarter.
Sources: Wikipedia — Siem Reap climate table; Vietnam National Authority of Tourism — weather and climate · last checked .
Who should skip this quarter
- Anyone who struggles in heat above 35 °C, especially at Angkor in April.
- Travellers who want to stay dry and keep electronics safe in the new year week in Thailand, Laos and Cambodia.
- Visitors hoping for clear mountain views in northern Vietnam in June, when storms begin.
- People who want a quiet visit to Cuc Phuong on the 30 April and 1 May holidays.
Common questions
Questions readers ask
When are Songkran, Pi Mai Lao and Khmer New Year in 2027?
Songkran is set at 13 to 15 April. Laos and Cambodia publish their 2027 holiday lists in advance; in 2026 both were 14 to 16 April. Check the official announcement before booking.
When can you see fireflies in Cuc Phuong?
Usually from late April to early May, in the evening. The park has run evening tours from 19:00 to 22:00.
Is April too hot for Angkor?
It is the hottest month, with average maxima around 36 °C. It is workable at sunrise and late afternoon.
Where is dry in June?
Central Vietnam, including Hoi An and Hue, is in its dry season until August.
Related
Read next
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.
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Calendar · Third quarter
July to September
The monsoon quarter: early rice in Tu Le and Mu Cang Chai, Mid-Autumn, waterfalls and the typhoon risk.
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Festivals · Thailand, Laos, Cambodia
April new year festivals
Dates and differences for Songkran, Pi Mai Lao and Khmer New Year, with the holiday week's transport and heat.
Read more
Nature seasons
Nature seasons
When the terraces turn gold, when buckwheat flowers on the Dong Van plateau, firefly evenings and monsoon waterfalls.
Read more
Planning
When not to go
Smoke season, typhoons, central Vietnam floods, extreme heat, holiday closures and advisories, with months.
Read more
Festivals
Festival calendar
Dates for 2026 and 2027 with a label for each: official, announced or calculated, and how the lunar calendars work.
Read more
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