Bay of Bengal cyclone to bring rain and snow to Nepal from Thursday night

A low-pressure system is developing over the Bay of Bengal and is expected to intensify into a powerful cyclone. For Nepal, that means a new spell of unsettled weather after much of the country had turned clearer following the monsoon’s withdrawal. Clouds are expected from Wednesday, followed by a rising chance of rain and snow.

The system’s influence should increase on Thursday. Rain is forecast across Koshi, Madhesh, Bagmati and Gandaki provinces, plus eastern Lumbini. Some Himalayan areas may receive snowfall, while hilly areas may also see rain. The cyclone’s west-north-west movement is expected to bring its influence closer to Nepal.

The strongest effects are expected from Thursday night through Friday and into Saturday afternoon. Meteorologists warn that rainfall amounts remain uncertain, but farmers and mountain travellers should prepare. Ripe paddy, drying grain, trekking routes and Himalayan journeys could all face weather-related problems.

Nepal’s weather may begin changing on Wednesday, when clouds are expected to build across parts of the country. Isolated showers could occur, and some Himalayan locations may receive snowfall. The main increase in rain is forecast from Thursday, when the cyclone’s influence becomes stronger.

From Thursday afternoon, rain could reach Himalayan and hilly areas of Koshi, Bagmati and Gandaki provinces. Meteorologists expect the system’s strongest period from Thursday night through Friday and into Saturday afternoon. Rain could become heavy in many places, including Kathmandu and districts in several provinces.

This timing matters because paddy harvesting is already under way, while trekking and mountaineering seasons are active. Farmers may need to bring crops indoors before Thursday. Trekkers and tourists already on Himalayan trails have been urged to move to safe locations and remain alert until the adverse weather passes.

The forecast points to the greatest weather risk in eastern and central Nepal. Rain is expected in Koshi, Madhesh, Bagmati and Gandaki provinces, along with eastern parts of Lumbini province. Kathmandu is also among the places where rainfall risk is considered comparatively high.

Some Himalayan and hilly areas of Koshi, Bagmati and Gandaki could receive rain from Thursday afternoon. Snowfall is possible in parts of the Himalayas, especially as the system affects higher locations. Pokharel identified 29 districts across five provinces as potentially at risk, though the exact rainfall amount remains uncertain.

The impact is expected to weaken farther west. Sudurpashchim and Karnali provinces may receive less influence than eastern areas. However, heavy rain could still occur from eastern Lumbini through Koshi. The system may initially affect the east and centre before spreading farther west, according to meteorologists.

The approaching weather could affect both agriculture and mountain tourism. Ripe paddy still standing in fields may be damaged by rain, while harvested grain left outside to dry could become wet. This is especially important because Nepal’s paddy harvest is already under way.

Meteorologists advise farmers to bring in their paddy before the worst weather or wait until it passes. Trekkers and tourists in Himalayan districts face another risk: rain, snow and changing conditions can make trails more hazardous. People already trekking have been told to move to safe locations.

The warnings cover the active trekking and mountaineering season, so many travellers may be in exposed mountain areas. The most difficult period is expected from Thursday night through Saturday. Exact rainfall and risk levels remain uncertain, but forecasts from several models point toward a comparatively high chance of rain.

Nepal is landlocked, but weather systems can move moist air far inland from the Bay of Bengal. A strengthening cyclone draws and pushes large amounts of humid air westward. That air can travel toward Nepal as the system moves west-north-west and approaches the Indian coast.

When moist air reaches Nepal’s hills and mountains, it is forced upward by the terrain. Rising air cools, and its water vapour can condense into clouds and rain. At high Himalayan elevations, temperatures can be low enough for that precipitation to fall as snow. The article’s forecast reflects this process, with rain expected in several provinces and snowfall possible in Himalayan areas.

The system’s effects may begin in eastern and central Nepal before spreading west. The strongest period is expected from Thursday night through Saturday afternoon. Although Nepal’s monsoon has withdrawn, this separate Bay of Bengal system can still produce another spell of rain and snow.

An upper-level trough is an elongated area of lower pressure high in the atmosphere. If it interacts with the Bay of Bengal system, the two weather features can support stronger upward motion. Rising air cools and forms more clouds, which can increase rainfall when enough moisture is present.

Pokharel warned that rainfall could intensify as the low-pressure system approaches Nepal and interacts with an upper-level trough. This mechanism could turn an already wet forecast into heavier rain across vulnerable areas. It could affect ripe paddy in fields and harvested crops left outside to dry.

The possibility is important because several weather models already indicate a similar likelihood of rain from Thursday through Saturday. Heavy rain is possible from eastern Lumbini to Koshi, while Kathmandu and other districts may also be affected. However, meteorologists stress that the final amount of rainfall and level of risk cannot yet be determined with certainty.

The South Asian monsoon is a seasonal circulation pattern that brings moist winds and widespread rain to South Asia during the warmer part of the year. Nepal depends on this rainy season for much of its annual water supply. Its arrival and withdrawal mark the region’s main wet and dry phases.

Nepal’s monsoon officially withdrew on October 14, and the weather had cleared across much of the country. The new threat is different: a low-pressure system over the east-central Bay of Bengal is strengthening and is forecast to become a cyclone. It may send another pulse of moisture toward Nepal.

That makes the forecast unusual because rain and snow are expected after the official monsoon withdrawal. Clouds may build from Wednesday, with heavier rain possible from Thursday through Saturday. Farmers are harvesting paddy, while trekkers and mountaineers are travelling, so this late-season weather could create fresh risks.