The monsoon season has officially entered Nepali territory, marking its onset three days earlier than the typical monsoon calendar. According to the Weather Forecasting Division of the Department of Hydrology and Meteorology, the monsoon entered the Koshi Province this morning.

Meteorologist Sanjeev Adhikari reported that the monsoon has commenced in the eastern districts of Taplejung, Panchthar, Ilam, and Jhapa, and is expected to spread across the country within 7 to 10 days. This year’s early arrival contrasts with last year’s monsoon, which began one day later than scheduled.

While the Koshi Province is experiencing monsoon rainfall, the meteorological officer highlighted that rainfall activities in other provinces, such as Gandaki, Lumbini, Karnali, and Sudurpaschim, are currently influenced by local and western winds rather than the monsoon.

Monsoon typically begins in the last week of May from the Bay of Bengal, affecting South Asian regions including Nepal. It enters Nepal from the eastern side via Bangladesh, usually 13 days after its onset in Kerala, India.

The South Asian Climate Outlook Forum (SASCOF) and the Meteorological Department forecast above-average rainfall for most parts of Nepal this year. There is a 35 to 55 percent chance of higher-than-average rainfall across the country, with specific forecasts indicating a 35 to 45 percent likelihood of heavy rain in the southern territories of Koshi, Madhesh, Bagmati, Lumbini, and Far West Provinces.

In Nepal, average monsoon rainfall is around 1,530 millimeters, with 80 percent of the annual rainfall occurring during the four-month monsoon period. Kathmandu sees an average annual rainfall of 1,454.8 millimeters. However, rainfall amounts vary significantly by region due to geographical differences.

The average duration of active monsoon rainfall in Nepal is 112 days. However, in recent years, the monsoon period has extended, with last year’s monsoon lasting 124 days. The department revised the monsoon calendar three years ago, now recognizing the monsoon period from June 13 to October 2, whereas it was previously from June 10 to September 23. The shortest recorded monsoon period was in 1979, lasting 73 days, while the longest was in 2008, lasting 130 days.