The Jain calendar is similar to the Hindu calendar. It follows the luni-solar system of reckoning, which means that it takes into account the movement of both the sun and moon while calculating the calendar. The lunar year is divided into 12 months. Each month has 29 - 30 days and starts with the new moon. A 13th month called Adhikamasa is added every three years to keep pace with the solar year.
The solar year too consists of 12 months. A solar month consists of the time taken by the sun to travel from one sign of the zodiac to the other. The day the sun moves into the next zodiac sign is called sankranti. A sankranti is considered extremely auspicious by the Jains. Many special prayers are performed on sankrantis.
A solar year is divided into six seasons of two months each:
Vasanta(spring) consists of March and April,
Grishma (summer) consists of May and June,
Varsha (the rains) of July and August,
Sharad (autumn) of September and October,
Hemanta (winter) of November and December, and
Shishira (the cool season) of Januaryand February.
The rainy period is a time when Jain ascetics are not allowed to travel. The time is spent in studying and preaching.
All days of the week are equally important to the Jain faith.