After reviewing recent reports, it is evident that Nepal has experienced unusually frequent rainfall, hailstorms, and snowfall during the pre-monsoon period, from Chaitra to Baisakh, resulting in an abnormally cool climate. The active western disturbance system has caused rainfall to be three times higher than usual during this phase, with cumulative precipitation reaching 230 millimeters by the end of Baisakh. Meteorologists forecast that the upcoming monsoon season may bring less rain and higher temperatures due to El Niño effects, urging people to stay alert. Kathmandu, 3 Jestha. Normally, the months from Chaitra to Baisakh in Nepal mark the peak of hot weather. However, this year’s conditions have been different, characterized by persistent rainfall and a sensation of cold, despite it being the warmer period of the year. The unusual experience of wearing jackets during what should be warm days is attributed to continuous precipitation. To understand why the rain persisted, one must consider atmospheric patterns extending to the ocean. Experts explain that the current increase in rainfall is linked to heightened activity of the pre-monsoon seasonal system, spanning mid-February to mid-May. Generally, this period is warm, but this year has seen repeated episodes of rain, hail, and snow through Baisakh, alongside occasional thunderstorms and strong winds in some areas. Meteorologists predict such weather may continue into Jestha.
Rainfall during this period primarily results from three factors: active western disturbances, local atmospheric conditions, and moisture-laden winds arriving from the Bay of Bengal. Western disturbances are air systems that move eastward from the Mediterranean region through Turkey, Iran, Afghanistan, and Pakistan into South Asia, carrying cool, moisture-rich air that causes rain and snowfall in Nepal’s Himalayan areas. Sometimes, these systems also bring hail and storms. Madan Sigdel, Associate Professor at Tribhuvan University’s Central Department of Hydrology and Meteorology, notes that the active western disturbances since the end of winter have led to snowfall and hail during this pre-monsoon phase. Explaining the frequent rainfall and cold sensations experienced during Chaitra to Baisakh, Sigdel says, “The greater post-winter activity of the western disturbances, combined with the recycling of local air and moisture, has increased rainfall.”
Meteorologist Ujjwal Upadhyay adds that a large cyclone (hurricane) in the Philippine Sea has generated an atmospheric system that has caused widespread rain from Indonesia and Sri Lanka to Thailand, Laos, Vietnam, and Nepal. The influence of western disturbances is expected to bring further rains in Nepal through Jestha. Dr. Vinod Pokharel, also an Associate Professor at Tribhuvan University’s department, confirms that some rainfall can still occur during the first few days of Jestha. The presence of clouds and rainfall has blocked sunlight from fully warming the Earth’s surface, contributing to the perception of cold weather. Nepal has observed cloudy weather with intermittent rainfall during the daytime and clear skies at night, allowing temperatures to drop sharply. According to meteorologists, thick clouds and storms during periods when solar radiation is normally at its peak have prevented surface warming, while clear night skies have accelerated temperature decreases, causing notable cold during mornings and nights even in Chaitra-Baisakh.
Rainfall Totals in the Pre-Monsoon Period
The pre-monsoon phase, spanning from the end of winter to before the monsoon onset, typically receives between 200 and 230 millimeters of rain throughout Nepal from mid-February to mid-May, with regional variations. Usually, Kathmandu gets about 100 millimeters of rainfall during this time, but by the end of Baisakh this year, it has received 230 millimeters, roughly three times the average. As rainfall is predicted to continue into Jestha, the total precipitation during this pre-monsoon period is expected to rise further. Presenting Kathmandu’s data, Upadhyay states, “Based on records of the last 45 years, the average rainfall in Baisakh and Jestha months should be around 100 millimeters, but 230 millimeters have already fallen by Baisakh 25, with more days of Baisakh remaining, meaning rainfall could reach triple the norm.” Historical data from 1981 to 2025 shows significant fluctuations in pre-monsoon precipitation. Ashok Bakhrel, a meteorologist, highlights that the highest pre-monsoon rainfall occurred in 1990 at 332.31 millimeters, followed by 322.85 millimeters in 2000, 317.9 millimeters in 2021, and 315.59 millimeters in 2020. In 2025, 274.21 millimeters were recorded. On the other hand, the lowest amounts were 138.01 millimeters in 1992, 141.56 millimeters in 1996, 154.91 millimeters in 2014, and 162.42 millimeters in 1995. Bakhrel notes that these figures indicate considerable variability in pre-monsoon rainfall. He also points out that eastern Nepal typically receives more than twice the pre-monsoon precipitation compared to western Nepal, with averages of 133.7 millimeters in the west, 250.9 in the central region, and 291.3 in the east. The main cause is believed to be moisture-bearing winds from the Bay of Bengal interacting with the Himalayan terrain.
Benefits and Challenges of Pre-Monsoon Rainfall
Normally, western disturbances bring precipitation and snowfall to the Himalayas and surrounding hills from Chaitra to Baisakh. Rain during the pre-monsoon period impacts agriculture, water availability, forest fires, and disaster risk management. This period coincides with the preparation of maize cultivation and rice transplantation, thus rain during this time is critically important for farmers. Experts say that continuous rainfall and temperature drops have immediately provided relief from heat and reduced forest fire occurrences. However, the sustained rainfall has also presented difficulties. Farmers have faced problems harvesting crops like wheat and lentils, while in some eastern Terai districts, farmers have struggled to prepare fields for growing mung beans and jute due to persistent rain, according to Rameshwar Rimal, Technical Officer at Nepal Agricultural Research Council’s National Agricultural Environment Research Centre. Hail and storms have damaged maize, banana, fruits, and vegetable crops. Excessive rainfall during Baisakh-Jestha increases the risk of soil saturation, heightening the possibility of landslides and floods during the coming monsoon season. Although meteorologists cannot definitively link pre-monsoon activity levels to monsoon rainfall intensity, global systems such as Pacific Ocean temperatures, Indian Ocean conditions, and jet streams are known to influence monsoon patterns in Nepal.
Currently, the Pacific Ocean temperature is higher than average, indicating El Niño conditions, while the Indian Ocean temperature remains neutral. The Department of Hydrology and Meteorology forecasts below-average rainfall and above-normal heat during the monsoon season this year. According to meteorologist Sudarshan Humagain, although some areas of Nepal may receive average rainfall, most places are expected to have below-normal precipitation. The variability and sensitivity of the weather have increased, with instances of no rain during rainy periods, excessive rainfall in some regions, and drought in others. Last year, drought conditions during the monsoon led to the declaration of drought-affected zones in the Madhesh region, and eastern Nepal suffered significant damage due to heavy rain and landslides well beyond the monsoon period. Meena Kumar Aryal, senior expert at the Department of Hydrology and Meteorology, advises caution because similar unpredictable conditions could recur this year: “Even after the monsoon starts, there might be dry spells and localized heavy rainfall, which can cause damage, so vigilance is essential.”
Meteorologist Dr. Vinod Pokharel describes this year’s El Niño as “particularly alarming,” warning of potential droughts in South Asia. In a Facebook post, he wrote, “Seasonal forecasts for the next six months indicate this situation may intensify problems. El Niño can trigger drought in South Asia.” Experts have linked rainfall unpredictability and instability to climate change, recommending climate adaptation planning. Madan Sigdel notes that recent weather events demonstrate that Nepal’s weather system is becoming more uncertain and sensitive. While some attribute these changes to climate change, Sigdel emphasizes the importance of first confirming climate change impacts and then adjusting traditional perceptions and strategies accordingly to develop appropriate programs.
