BMKG Weather Forecast: North Sumatra on Alert for Heavy Rain Over the Coming Week

The Meteorology, Climatology, and Geophysics Agency (BMKG) has issued an early warning regarding the potential for rain in parts of North Sumatra over the coming week. These conditions are triggered by wind shear and active atmospheric wave activity monitored in the region.

Putri Hafizah, a forecaster at BBMKG Region I Medan, explained that in addition to these atmospheric factors, fairly unstable air conditions are significantly supporting convective processes and the formation of rain clouds. “The presence of a cyclone seed in the Indian Ocean west of Sumatra is also triggering the formation of wind shear and convergence areas along the west coast to the eastern slopes of North Sumatra,” Putri stated in Medan on Tuesday (4/8/2026).

Another factor strengthening the potential for this extreme weather is warm sea surface temperatures, which increase evaporation and rain cloud formation. BMKG noted that in the mornings to afternoons, the weather is generally sunny and cloudy. However, this condition actually triggers significant surface heating, which then stimulates the growth of convective clouds in the late afternoons to evenings. As a result, several areas in North Sumatra are likely to experience moderate to heavy intensity rain accompanied by lightning and short-duration strong winds.

BMKG’s weather forecast for the coming week indicates that rain will dominate almost all districts and cities in North Sumatra. The public is urged to remain vigilant against potential hydrometeorological disasters such as floods, waterlogging, and landslides, especially for residents living in mountainous slope areas and along riverbanks.