Heavy rain, high temperatures expected this monsoon

KATHMANDU: The upcoming monsoon season, set to begin in about six weeks, is projected to bring above-average rainfall across much of South Asia, including Nepal.

This forecast was presented at the South Asian Climate Outlook Forum (SASCOF) held recently in Pune, India.

According to Sudarshan Humagain, a meteorologist with Nepal’s Department of Hydrology and Meteorology who participated in the forum, the long-range forecast is based on analyses from multiple global weather models. “Current projections indicate a higher-than-average monsoon for Nepal. However, an updated forecast will be released in mid-May, which may reflect some changes in conditions,” said Humagain.

While certain northern, southern, eastern, and northeastern regions of South Asia may receive normal or slightly below-normal rainfall, Nepal is expected to witness significantly higher rainfall compared to previous years.

Last year’s monsoon brought 1,670.7 mm of rainfall—122% of the average—and lasted 13 days longer than usual.

El Nino & its influence on the monsoon

One of the major climate systems influencing the South Asian monsoon is the El Nino–Southern Oscillation (ENSO).

Currently, the ENSO is in a neutral state, meaning neither El Nino nor La Nina conditions are dominant.

Forecasts suggest that this neutral phase is likely to continue through the upcoming monsoon and into the winter season.

Historically, El Nino conditions tend to suppress rainfall, while La Nina enhances it.

Under neutral conditions, however, Nepal generally experiences normal to above-average rainfall.

This trend increases the probability of a wet monsoon for the country this year.

IOD & N. Hemisphere snow cover also at play

Meteorologists also point to the Indian Ocean Dipole (IOD) and snow accumulation in the Northern Hemisphere as key influencers of monsoon patterns.

Both the IOD and Northern Hemisphere snow levels are currently neutral, with projections suggesting this will remain steady into the monsoon season.

Notably, reduced snowfall in the Northern Hemisphere could contribute to increased rainfall in Nepal.

Higher temperatures expected during monsoon

Alongside the expected heavy rainfall, minimum temperatures during the monsoon are also predicted to be higher than average—a potential indicator of ongoing climate change.

The regional forecast was developed with participation from meteorological agencies across the SAARC nations and Myanmar, in collaboration with international experts, under the initiative of the United Nations’ meteorological body.

These monsoon outlooks have been regularly issued in recent years to help governments prepare for seasonal climate impacts.