Hindu Festivals

Haipusam - Mostly a Tamil festival, commemorating the birth of Lord Murugan. Late Janurary - Early Feburary.
Makar Sankranti
Maha Shivratri - Festival to honor Lord Shiva. Feburary - March.
Ugadi / Gudhi Padwa / Baisakhi/Vaisakhi / Bihu / Poila Baisakh - New Year's Day in various
Holi
Rath Yatra{Cart Festivals}
Ram Navami - Commemorates the marriage of Seetha and Rama, and also the birth of Lord Rama. April.
Krishna Jayanti - Commemorates the birth of Lord Krishna. August - September.
Ganesh Chaturthi - Commemorates the birth of Lord Ganesha. Late August to Early September.
Vijayadasami - Celebrates the victory of good over evil. September - October.
Diwali - The most widely celebrated festival, and is known as the "festival of lights". Occurs on a new moon day, usually in October or November.
Diwali Amvasaya (Laxmi Puja)
Diwali (day 2)
Bhaubeej

Islamic festivals

Eid ul-Fitr
Eid ul-Adha (Bakrid)
Ramadan

Christian festivals

Christmas Day
Good Friday

Sikhism festivals

Guru Nanak's Birthday Jayanti
Guru Govind Singh's Birthday Jayanti
Guru Teg Bahadur's Martyrdom Day
Vaisakhi

Buddhism festivals

Buddha Jayanti

Jainism festivals

Mahavir Jayanti