The Mahanawami is observed on the ninth day of the waxing moon in the month of Asoj as per the lunar calendar. It is also marked as part of the 10-day Bada Dashain festival.
Special worship is performed to Durga Bhawani on the occasion of the Mahanawami and the 'jamara' which have been germinated is offered to the goddesses at various shrines.
He-goats, ducks, roosters and he-buffalos are sacrificed at the various temples dedicated to the goddesses. Those who do not have the tradition of offering animal or bird sacrifices, offer the sacrifice of fruits and vegetables to the goddess.
The Durga Saptasati and Devi Strota scriptures are also recited at home and in temples on this day.
As mentioned in the Markandeya Purana scripture, the Goddess Chamunda had slain the demon Raktabij on the day of Mahanawami. So, the special worship of the goddess on this day with the offering of animal sacrifices.
Vehicals are also worshipped on this day.
On this day, the security forces also perform what is called the 'kot puja' or worship of the armouries.
The Taleju Temple located at Hanumandhoka in the capital is also opened for the devotees to pay homage on this day. It is opened only on the occasion of the Mahanawami.
The people of the Newar community also worship Bhimsen, a Hindu deity, by making animal sacrifices today on the occasion of Mahanawami.