TEMPO.CO, Jakarta – Indonesia’s Meteorology, Climatology, and Geophysics Agency (BMKG) has warned residents in parts of North Sumatra to remain alert for rain that could trigger floods and landslides on Wednesday, June 24, 2026.
BMKG forecaster Endah Paramitha from its Region I Meteorological Station in Medan said rainfall accompanied by lightning and strong winds could occur in the western and eastern slopes of North Sumatra.
“Residents should be aware of the potential for rain accompanied by lightning and strong winds in the western and eastern slopes of North Sumatra, which could lead to disasters such as floods and landslides,” Endah said on Tuesday.
According to BMKG, atmospheric conditions in North Sumatra remain unstable, creating favorable conditions for convection processes and the formation of rain clouds, which are expected to be mostly localized.
Why Is Rain Expected in North Sumatra?
Endah said wind analysis showed the presence of wind convergence zones around North Sumatra, which could contribute to increased cloud formation in several areas.
Weather conditions in the province are also being influenced by a shearline, or wind direction change, which supports rising air movement and the development of rain clouds.
In addition, active Kelvin Wave activity over northern Sumatra is also contributing to the growth of convective clouds, increasing the potential for rainfall.
Weather Forecast
BMKG forecasts cloudy conditions and light rain in many parts of North Sumatra on Wednesday morning.
From afternoon to evening, light to moderate rain is expected in areas including Deli Serdang, Langkat, North Labuhanbatu, Simalungun, and surrounding areas.
Rain is expected to continue into the night in several parts of the province. Moderate rainfall is possible in Labuhanbatu, North Labuhanbatu, Langkat, and Mandailing Natal, while most areas are expected to be cloudy by early Thursday morning.
Temperatures are forecast to range between 15 and 31 degrees Celsius, with humidity levels reaching 78–99 percent. Winds are expected to blow from the south to southwest at speeds of 3–7 kilometers per hour.
Read: Why Has Indonesia Seen Recent Rainfall During the Dry Season?
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