According to Hindu :-
January/February (Magh) Mahashivratri
A celebration honour of Lord Shiva held at all the principal Shiva temple, such as the Rudershwar, Mangueshi, Nagueshi, Sri Madadev - Bhumika and other temples. Rantha Saptami festival takes place in February at the Mallikarujuna Temple. Maruti-Zatra at Shri Mahalakshmi Temple is presiding deity of Panaji, Goa's capital city. Mahalasa Jatra or Vijayarathotsav (Chariot Festival) is celebrated at Mahalasa Temple of Mohini in Ponda.
Shigmotsavor or Shigmo: All over Goa, Special celebrations at Panaji, Mapusa, Vasco Da Gama and Margoa. A Spring festival celebrated on the full moon day of the month of Phalgun in March.It is a grand five day festival of colour, celebrated distinctively in the villages, corresponding with Holi or Spring Festivals. Shigmo is universally celebrated in Goa, but specially in Panaji, Mapusa, Vasco Da Gama and Margoa.
Ghodemodni or Parade of the horse riders, is part of Shigmo and is found in Fatorpa and Bicholim. Hypnotic and rhythmic music of drums and Whistles accompany the martial dance, which Parades down the main street, imitating horses and their riders.
Rombat takes place on the second and third day of Shigmo. It is a Procession of men in traditional dress carrying banners and umbrellas dancing to the music of drums. Young boys wave green twigs, signifying the arrival of spring
Drama Festivals form an important part of Shigmo with most villages staging plays during the week.
Holi is celebrated as Gulal or Rangapanchami at Sri Damodar Temple in Zambaulin.
The three day festival of Gade at Mahadev Bhumika Temple attracts huge crowds.
Kalas Utsav is celebrated on a major scale every alternate year at Sri Morjaee Temple in Pernem. Visitors from Maharashtra and Karnataka attend the seven day festivities which are socio religious occasions.
Ram Navami or the birthday of Lord Rama is celebrated at Ramnath temple. Chaitra Purnima is celebrated at Sri Mahalakshhmi Temple at Panaji, and during the nine days preceding the full moon , at Sri Vithal Temple in Sanquelim. It is also Nagueshi, Chandranath, Cudnem and Mashem in Canacona.
This is home coming season for many Goan settled away from Goa. It is also the fruit season and Feni making season. A distinctive Goan aperitif, Feni comes from cashew apples. In addition it is toddy- tapping season.
Mirg is on 6th June. It is the start of the Monsoon season. The Christian Mirg is one day earlier. If the rains fail, prayers are offered to the Catholic saints born this month-- St. Anthony, St. John the Baptist and St. Peter and St. Paul. In Goa there is happy mingling of festivals and feast days for the common good of all.
Rainy season with no major festival.
July- August (Shravana)
Gokul Ashtami or Janamashtami is the Birthday of Lord Krishna. This marks the beginning of Goa's harvest festival. At Narve village in Bicholim, people gather for pilgrimage from far and wide.
August- September (Bhadra-Pada)
Ganesh Chaturthi birthday of Lord Ganesh, the most important deity in the Konkan, and is celebrated all over Goa. Thousand return to Goa for this festival, which is associated with good Harvest.
Novidade In each village, the first offering is is made to the church and the paddy specially blessed. No farmer, will harvest his rice crop before it is offered in a ceremony called 'Novidade' in which the parish priest himself harvests sheaf of rice and returns with it to the Church, Local people accompany him with music, fire works and Jubilation . It is a true feast day for all. Women folk of Goa's earliest tribal settlers perform a dance called Bhandup in half second half of the month.
August- September (Ashwin)
Navarati or the nine nights festivals associated with Lord Rama's Defeat of Ravana, demon King of Lanka culminates in the grand festival of Dusshera. Dusshera is celebrated by devotees of the Mother Goddess as her festival. The Sri Bhagavati Temple is Pernem has a fortnight's festivities on the occasion. Special celebrations for Navaratar Utsav are held at Shantadurga, Nagueshi, Mahalakshmi and Ramnath Temples at Ponda and at Kalika Devi Temples in Kasarpal. The Dhangar Dance is dance of worship performed during this festival. The Kiran Mahotsasv or religious music festival takes place at Quepem in September and is an all night celebration.
October- November (Kartika)
Deepawali is the great festivals of lights . It is universally celebrated in Goa, in homes, on the streets, in shops and of course, in religious places.
November- December (Aghrana)
Kejagiri Purnima could fall early in lights. It is the full moon following Dusshera and at Mardol in Ponda there are special celebrations to mark this auspicious day.
November- December (Paush)
Malni Purnima is the festivals at Sri Devaki Krishna Temple at Marcel. The Zatra of Shri Shantadugra is held at Dhargal in Pernem. The deity is taken out of the temple in a colourful procession for the day. The annual Zatra of Shri Shantadurga at Kunkoliemkarin at Fatorpa in Quepem also falls in this month. Thousands flock to attend the festival from afar. Zatra in all Temples, of special importance being at Mangueshi, Nagueshi, Ramnathi, Kavlem, Madki, Kundai, Shiroda, Khandepar, Borim, Kapileshwari, Mulgaon, Fatorpa, Amona, Mashel, Mala-Panaji, Mapusam, Velinga, Karmali, and Calangute.
The Datta Jayanti is celebrated as the annual festival at Shri Datta Temple at Dattawadi, Sanquelim.
According to Christian
January 6 ----- Feast of the Three Kings at Reis Magos, Cuelim (Canasaulim) and Chandor.
February 2 ---- Feast of our Lady of Chandelaria at Pomburpa.
5th Monday in Lent ---- Procession of all Saint of the Franciscan Third Order (only other besides Rome) at Goa Velha.
1st Sunday after Easter --- Feast of Jesus Nazareth at Siridoa.
16 days after Easter -- Feast of Our Lady of Miracles at Mapusa.
24th June --- Feast of Sao Joao (St. John Baplist).
24th August-- Festivals of Novidades -- Offering of first sheaves of rice crop to the head of State.
1st Fortnight of October ---- Fama De Menino Jesus at Colva.
3rd Wednesday of November --- Feast of Our Lady of Rosary at Navelim.
3rd December --- Feast of St. Francis Xavier, Patron Saint Goans, at old Goa. This occasion draws thousands of faithful to Goa to participate in the religious event.
8th December --- Feast of our Lady of Immaculate Conception at Panaji and Margoa.
25th December --- Christmas, all over Goa with the customary Midnight Mass on gatherings and special Christmas Eve and with prayers gathering and special Christmas festivals. A Goan will leave his front door open during the festival as a gestures of generosity toward all who may visit his home.
According to Muslim
17th Zilhaj (February) ---- Urus of Shah Abdullah at Ponda.