Whatever time of year you visit, you will almost certainly experience some festival or other. Underneath are the most notable. There is usually some type of celebration in the temples at full moon.
February: Shivaratri is the festival held in honour of Shiva. During full moon in the month of phalgun, festivals are held around the numerous Shiva temples.
February/March: Holi is a popular festival, especially amongst the lower castes. This is due mainly to the fact that all rules and norms are thrown out of the window and everything goes. During Holi, everybody splashes each other with water and powder paint. Make sure that you wear old clothes, as tourists are a popular target and the paint is not easy to get out! Holi marks the beginning of the spring.
April/May: Bisket, the Nepalese New Year festival, is celebrated. Statues of gods are towed through the towns on temple-wagons, and everyone takes the day off.
September/October: Durga Puja or Dasain is the largest festival in Nepal. It lasts for around 10 days and is celebrated everywhere. It marks the defeat of the buffalo demon Mahisha by the goddess Durga. There are kite-flying competitions, parades and processions in the Kathmandu Valley.
End of October/Beginning of November: Diwali or Tihar is celebrated, the Festival of Light. It is marked by the illumination of thousands of lights, fireworks, baking cakes and making sand patterns outside one’s front door. This is to welcome the god Rama back from his long exile in the jungle.