The Balinese has their own calendar system. Two, in fact, running in parallel.

• Sasih
  The Sasih cycle is a 12 lunar month calendar system. Each month begins on the day after a new moon (tilem). The middle of each month is the full moon (purnama).
• Pawukon
  The Pawukon calendar system is believed to be indigenous to the Balinese, possibly rooted in the thousand-year-old rice-growing cycle of the island. There are six months to a Pawukon year, and 35 days to a Pawukon month. So a Pawukon year is 210 days. Each Pawukon month is divided into many shorter cycles (weeks) that run concurrently. The most important weeks are the 3, 5, and 7 day weeks

Certain days of the Sasih are considered important, namely tilem and purnama. Temple anniversaries and festivals usually occur on a purnama. Days prior to a Sasih new year, the whole island participates in celebrations and presenting offerings and performing ritual temple cleansing. The climax is the day of the new year: Nyepi. On this day, the entire island goes into reflection and meditation, shutting down everything, including electricity. So, don't be surprised if your hotel manager asks you to close your curtain on a Nyepi day.

On the Pawukon cycle, certain conjunction of the different week cycles are considered significant. On these days, ceremonies and sacred dances are performed in the temples, or people immerse themselves in prayers and meditation.