KATHMANDU, JUNE 16 Nepal's monsoon is running late, and a developing El Niño in the Pacific Ocean may be partly to blame, the Department of Hydrology and Meteorology (DHM) has warned, even as pre-monsoon rain and thundershowers continue to bring some relief to hilly and Himalayan regions. The department on Monday confirmed that the monsoon had not yet entered Nepal as of that date, normally expected around June 13, and that satellite data and numerical weather forecasting models suggest the arrival could be delayed by a few more days. The department noted that western wind activity, combined with local winds, has been keeping parts of Koshi, Bagmati, and Gandaki Provinces' hilly and Himalayan zones active with cloud formation, thunder, and mid-level rainfall in the interim. El Niño casts a long shadow The department flagged the emergence of El Niño conditions in the Pacific as a significant concern for the season ahead. El Niño, a periodic warming of Pacific Ocean surface temperatures, has historically delayed and weakened monsoon onset across South Asia, including Nepal. The department noted that in previous El Niño years, Nepal's monsoon arrival was pushed back considerably - with late arrivals recorded in 1972 (June 15), 1982 (June 20), 1983 (June 28), 1987 (June 14), 1992 (June 21), 1997 (June 14), 2002 (June 15), 2009 (June 23), 2015 (June 15), 2019 (June 20), and 2023 (June 14). With El Niño now developing in the Pacific and forecast to intensify, the department said the monsoon could weaken over Nepal and the broader South Asia region. It urged the public to follow weather forecasts regularly and stay updated on meteorological advisories throughout the monsoon season. Today's weather picture Meanwhile, the department's 24-hour forecast for Tuesday, June 16 paints a mixed picture across the country, pre-monsoon activity keeping the hills and mountains unsettled, while the plains bake under intense heat. Partly cloudy conditions are expected over the hilly and Himalayan regions, with light to moderate rainfall and thundershowers accompanied by lightning possible at several locations, along with snowfall at a few high-altitude points. The Terai of Koshi Province and parts of Madhesh, Bagmati, Gandaki, and Lumbini provinces may also see isolated showers. However, hot day conditions are forecast for parts of the Terai in Lumbini and Sudurpashchim provinces, with temperatures expected to be among the highest in the country. Among major cities, Dhangadhi and Nepalgunj are forecast to reach 38 to 40 degrees Celsius under hot day conditions, with Bhairahawa not far behind at 37 to 39 degrees. Pokhara and Biratnagar face the highest rainfall probability today at 60 and 40 percent respectively, with moderate thundershowers expected. Kathmandu can expect light rain and thunderstorms with a 40 percent probability of rain, temperatures ranging between 29 and 31 degrees through the day and dropping to 19 to 21 degrees overnight. Taplejung faces a 60 percent chance of moderate rain and thundershowers, with the range between 26 and 28 degrees. At the cooler end of the spectrum, Jomsom is forecast between 22 and 24 degrees with a 30 percent chance of rain, while Jumla sits at 27 to 29 degrees with a similar outlook. The overnight low at Jomsom could drop to as low as 9 to 11 degrees. The department said it is continuously monitoring the monsoon system and will issue updates as conditions develop.