Nepal is 5¾ hours ahead of GMT/UTC; this curious time differential is intended to make it very clear that Nepal is a separate place to India, where the time is 5½ hours ahead of GMT/UTC. There is no daylight-saving time in Nepal.
When it’s noon in Nepal it’s 1.15am in New York, 6.15am in London, 1.15pm in Bangkok, 2.15pm in Tibet, 4.15pm in Sydney and 10.15pm the previous day in Los Angeles, not allowing for daylight saving or other local variations.
Nepali holidays and festivals are principally dated by the lunar calendar, falling on days relating to new or full moons. The lunar calendar is divided into bright and dark fortnights. The bright fortnight is the two weeks of the waxing moon, as it grows to become purnima (the full moon). The dark fortnight is the two weeks of the waning moon, as the full moon shrinks to become aunsi (the new moon).
The Nepali New Year starts on 14 April with the month of Baisakh. The Nepali calendar is 57 years ahead of the Gregorian calendar used in the West, thus the year 2018 in the West is 2075 in Nepal.
The Newars of the Kathmandu Valley, on the other hand, start their New Year from the day after Deepawali (the third day of Tihar), which falls on the night of the new moon in late October or early November. Their calendar is 880 years behind the Gregorian calendar, so 2018 in the West is 1138 to the Newars.