In the Buddhist calendar there are three seasons (utu) a year: hot, wet and cool seasons (gimha, vassa, hemanta). There are eight fortnights (pakkha) per season, though in some years, an extra month (adhikamāsa) is added to one of the seasons, making ten fortnights in that season. There are seven such extra months every nineteen years.
The commentaries (see table below) say that all fortnights have fifteen days, except the 3rd and the 7th fortnights, which have fourteen days xx>footnote. Vinaya, however, allows communities to decide for themselves whether to end any particular fortnight on the 14th day or 15th day (Vin.1.132), and to mark the day with the uposatha recitation (Vin.1.104) or pavarana ceremony (Vin.1.160).
The fortnights are best called either ‘waning fortnights’ (kāḷapakkha) or ‘waxing fortnights’ (sukkapakkha) (A.2.19; A.5.19). The half-moon day is the 8th day of either fortnight. The day after the full-moon day is the first day of the next month.
Season |
Month | Waxing fortnight: uposatha day |
Waning fortnight: uposatha day |
| Hot (gimha) | Citta (March-April) | 1st fortnight: 15th day | 2nd fortnight: 15th day |
| Hot | Vesākha (April-May) | 3rd fortnight: 14th day | 4th fortnight: 15th day |
| Hot | Jeṭṭha (May-June) | 5th fortnight: 15th day | 6th fortnight: 15th day |
| Hot | Asāḷha (June-July) | 7th fortnight: 14th day | 8th fortnight: 15th day |
| Wet (vassa) | Sāvana (July-Aug) | 1st fortnight: 15th day | 2nd fortnight: 15th day |
| Wet | Poṭṭhapāda (Aug-Sep) | 3rd fortnight: 14th day | 4th fortnight: 15th day |
| Wet | Assayuja (Sept-Oct) | 5th fortnight: 15th day | 6th fortnight: 15th day |
| Wet | Kattika (Oct-Nov) | 7th fortnight: 14th day | 8th fortnight: 15th day |
| Cool (hemanta) | Māgasira (Nov-Dec) | 1st fortnight: 15th day | 2nd fortnight: 15th day |
| Cool | Phussa (Dec-Jan) | 3rd fortnight: 14th day | 4th fortnight: 15th day |
| Cool | Māgha (Jan-Feb) | 5th fortnight: 15th day | 6th fortnight: 15th day |
| Cool | Phagguna (Feb-March) | 7th fortnight: 14th day | 8th fortnight: 15th day |
The first rains residence period (vassa) begins on the first day of Sāvana and ends on the last day of Assayuja; the second vassa begins and ends a month later. However, the Buddha allowed monks who need to leave their rains residences, to do so for up to seven days. If this means leaving seven days before pavarana, they have no obligation to return (so sattāhaṃ anāgatāya pavāraṇāya sakaraṇīyo pakkamatī. āgaccheyya vā so bhikkhave bhikkhu taṃ āvāsaṃ na vā āgaccheyya, tassa bhikkhave bhikkhuno purimikā ca paññāyati paṭissave ca anāpatti) (Vin.1.155). This shows that pavarana marks the end of the rains residence period. Therefore, if monks spend the whole vassa, they can leave their rains residences immediately after the pavarana ceremony. In some countries, however, it is traditional for monks to stay till the following day, perhaps because that is when lodgings for the following vassa are traditionally allocated (Vin.2.167).
xx>footnote (Samantapāsādikā 1035,14–16; Kaṅkhāvitaraṇī 5,2–5: quoted Petra Kieffer-Pülz, “Old and New Ritual” Indica et Tibetica Verlag, Marburg 2006)
