The Festival of Colors, Holi in Nepal, also known as Phagu Purnima, commemorates the arrival of spring and the triumph of good over evil.  Hindu mythology, particularly the story of Prahlad and Holika, is its foundation.
Rituals: Holika Dahan (bonfire night), which represents purification, is the first ritual.  Colored powders, water fights, music, dance, and festive food are all part of Rangwali Holi the following day.
Nepalese festivities:

Pokhara: Highlights Phewa Lake with performances and even paragliding with a Holi theme.
Terai: Nepali-Indian customs mixed with folk music and grand processions.
Hilly areas: More conventional, with natural or herbal hues.