Adhi Poson Poya (අධි පොසොන් පොහොය) is an extra full moon Poya day that appears in Sri Lanka only in years when the Buddhist lunar calendar adds a thirteenth month. In 2026 it falls on Saturday 30 May, four weeks after Vesak and one lunar month before the regular Poson Poya on Monday 29 June. Like every Poya, it is a public and bank holiday across the island, which is why 2026 has thirteen Poya holidays instead of the usual twelve.
What "Adhi" Means
Adhi means additional. Sri Lanka's Buddhist and traditional calendar counts months by the moon: each month ends at a full moon, and that full moon is its Poya. Twelve lunar months come to about 354 days, roughly eleven days shorter than the solar year of 365 days. Left alone, the months would slowly drift away from the seasons, and festivals tied to the monsoon, the harvest and the Sinhala and Tamil New Year would wander through the year.
To keep the two in step, an extra lunar month, the adhi masa, is inserted about once every two to three years. The new month borrows the name of the month it doubles, and its full moon becomes an Adhi Poya. Which month is doubled changes from one leap year to the next, so other years have seen an Adhi Esala or an Adhi Duruthu Poya instead. In 2026 the extra month is Poson.
Adhi Poson Poya in 2026
- Vesak Poya: Friday 1 May 2026, with the following day also a holiday.
- Adhi Poson Poya: Saturday 30 May 2026.
- Poson Poya: Monday 29 June 2026.
The full list, with every public and bank holiday of the year, is on our Sri Lanka public holidays calendar.
How It Is Observed
For Sri Lankan Buddhists, Adhi Poson Poya is a Poya like any other: a day for the temple rather than a festival in its own right. Families dressed in white bring flowers and light oil lamps at the stupa and the Bodhi tree, listen to Dhamma sermons, and many spend the whole day at a temple to observe sil, keeping the eight precepts from dawn to dawn.
The great Poson celebrations, which mark the arrival of Arahat Mahinda and the beginning of Buddhism in Sri Lanka, belong to Poson Poya itself. Pilgrims climb the stone steps of Mihintale on the Poson full moon, and Anuradhapura fills with illuminated pandals, processions and roadside dansalas giving free food and drink. In a year with an Adhi Poson, many temples start their Poson preparations around the extra full moon, but for the main pilgrimage, plan around the regular Poson date.
What It Means for Visitors
- Alcohol. As on every Poya, the sale of alcohol is prohibited, so liquor shops and bars close and many hotels do not serve alcohol in public areas.
- Banks and offices. Government offices and banks close. Most shops, restaurants and tourist sites stay open, though some small businesses take the day off.
- Temples. Temples are at their busiest. Dress modestly, in white or light colours if you can, with shoulders and knees covered, and remove shoes and hats before entering temple grounds.
- Travel. Buses and trains towards major temples are busier than usual. In 2026, Adhi Poson falls on a Saturday, so expect a full weekend of local travel.
The Other Poya Days
Each of the twelve regular Poya days commemorates its own event in the life of the Buddha or in the history of Buddhism in Sri Lanka. See them all, month by month and with this year's dates, on our Poya days page, or read about the Poson Poya that Adhi Poson precedes on the Poson Poya page.