The Great Festival (Maholsav) of the temple flags on the day of 'Thiruvathira' in the month of 'Dhanu' (Malayalam Era) occurs every year, which falls either in the last week of December or in the first week of January. "Thiruvathira" is the birth star of Lord Shiva. The duration of this festival is 8 days, and the holy dip of the deity takes place on the morning of the eighth day.

It is also one of the important festival at Vadukunna . Mahashivaratri Festival or the 'The Night of Shiva' is celebrated with devotion and religious fervor in honor of Lord Shiva, one of the deities of Hindu Trinity. Shivaratri falls on the moonless 14th night of the new moon in the Hindu month of Phalgun, which corresponds to the month of February - March in English Calendar. Celebrating the festival of Shivaratri devotees observe day and night fast and perform ritual worship of Shiva Lingam to appease Lord Shiva.
There are various interesting legends related to the festival of Maha Shivaratri. According to one of the most popular legends, Shivaratri marks the wedding day of Lord Shiva and Parvati. Some believe that it was on the auspicious night of Shivaratri that Lord Shiva performed the 'Tandava', the dance of the primal creation, preservation and destruction. Another popular Shivratri legend stated in Linga Purana states that it was on Shivaratri that Lord Shiva manifested himself in the form of a Linga. Hence the day is considered to be extremely auspicious by Shiva devotees and they celebrate it as Mahashivaratri - the grand night of Shiva.
Various traditions and customs related to Shivaratri Festival are beutifully followed by the worshippers of Lord Shiva. Devotees observe strict fast in honor of Shiva, though many go on a diet of fruits and milk some do not consume even a drop of water. Devotees strongly believe that sincere worship of Lord Shiva on the auspicious day of Shivaratri, absolves a person of sins and liberates him from the cycle of birth and death. Shivaratri is considered especially auspicious for women. While married women pray for the well being of their husbands unmarried women pray for a husband like Lord Shiva, who is regarded as the ideal husband.
To mark the Shivratri festival, devotees wake up early and take a ritual bath, After wearing fresh new clothes devotees visit the Vadukunna Shiva temple.
It is only on the following morning that devotee break their fast by partaking prasad offered to the deity. Auspicious festival of Mahashivaratri falls on the 13th or the 14th night of the new moon during Krishna Paksha in the Hindu month of Phalgun. The Sanskrit term, Krishna Paksha means the period of waning moon or the dark fortnight and Phalguna corresponds to the month of February - March in English Calendar. Shivaratri Festival is celebrated on a moonless night.