Exceptionally rare Tropical Cyclone Senyar kills more than 300 across Indonesia, Malaysia and Thailand
A low-pressure area developed over the Strait of Malacca on November 22, 2025, and gradually organized into Cyclonic Storm Senyar on November 26. The rare low-latitude system made landfalls in northern Sumatra and Peninsular Malaysia, producing extreme rainfall and catastrophic flooding across Indonesia, Malaysia, and southern Thailand. At least 316 people were killed and thousands displaced before Senyar weakened into a low-pressure remnant on November 28.
Satellite image of Tropical Cyclone Senar at 01:50 UTC on November 26, 2025. Credit: JMA/Himawari-9, Zoom Earth, The Watchers
- Cyclonic Storm Senyar was only the second documented tropical cyclone in the Strait of Malacca, and the first since Tropical Storm Vamei in 2001. Forming near 3° N, where the Coriolis force is normally too weak for tropical cyclogenesis, it represents an exceptionally rare equatorial cyclone likely aided by warm seas, cross-equatorial flow, and an active Madden–Julian Oscillation phase.
- The storm produced extreme rainfall, widespread flooding and landslides across northern Sumatra, Peninsular Malaysia, and southern Thailand, destroying homes, roads, and bridges. Entire districts such as Sibolga (Indonesia) and Songkhla (Thailand) experienced severe infrastructure losses, mass evacuations, and ongoing humanitarian operations.
- Across Indonesia, Malaysia, and Thailand, Senyar caused more than 316 fatalities, including 169 in Indonesia and 145 in Thailand, with hundreds injured or missing and thousands displaced throughout the region.
Cyclonic Storm Senyar formed from a low-pressure area that developed over the Strait of Malacca on November 22. It was the thirteenth tropical depression and third cyclonic storm of the 2025 North Indian Ocean cyclone season. The disturbance intensified into a depression and deep depression on November 25 before reaching cyclonic-storm strength on November 26.
The Joint Typhoon Warning Center (JTWC) classified it as a minimal tropical storm with sustained winds of about 65–75 km/h (40–45 mph).
The India Meteorological Department (IMD) reported that Senyar made landfall on northern Sumatra near midnight local time on November 26, then paralleled the Sumatran coast while weakening slightly before making a second landfall in Peninsular Malaysia between Selangor and Negeri Sembilan around 00:30 MYT on November 28.
The Malaysia Meteorological Department (MetMalaysia) and IMD declared the system a low-pressure remnant later that day as it moved northeast toward southern Thailand and the South China Sea.
Intense convective thunderstorms produced extreme rainfall across western Sumatra, triggering flash floods and landslides that devastated multiple districts. Sibolga and the surrounding Tapanuli region suffered extensive damage to homes, roads, and bridges.
Indonesia’s National Disaster Management Agency (BNPB) confirmed 169 fatalities, 113 injuries, and 154 people missing as of November 28. Thousands were displaced as floodwaters inundated coastal and upland settlements.
Emergency teams supported by the Indonesian National Armed Forces (TNI) and police continue to reach isolated areas where debris flows have blocked access. BNPB warns that saturated soils and ongoing rainfall could trigger further landslides even after the storm’s dissipation.
After crossing the Strait, Senyar brought severe weather to Peninsular Malaysia. MetMalaysia reported widespread flooding in Perak, Kedah, Kelantan, and Penang, together with coastal inundation and rough seas along the west coast. Although wind speeds had weakened, persistent rain caused significant river flooding and road closures.
The remnant circulation then moved over southern Thailand, where it maintained strong convective bands. Thailand’s Department of Disaster Prevention and Mitigation (DDPM) reported heavy flooding and landslides across at least 10 provinces, particularly Songkhla, Phatthalung, Trang, and Nakhon Si Thammarat.
At least 145 people were killed in Thailand, including 110 in Songkhla, according to preliminary regional summaries.
Combined, the cyclone caused more than 316 deaths across Indonesia, Malaysia, and Thailand by the end of November 2025.
Although Senyar has lost tropical-storm characteristics, its remnants continue to bring periods of heavy rain to parts of northern Sumatra, Peninsular Malaysia, and southern Thailand. Both MetMalaysia and BMKG have maintained warnings for flash floods and landslides in saturated areas and advised residents in flood-prone zones to remain alert.
Senyar formed under rare cross-equatorial flow and active MJO phase
Tropical cyclones typically form at least 5° from the equator, where the Coriolis force is strong enough to induce rotation. The Strait of Malacca, between roughly 2° and 6° N, rarely meets this condition.
Meteorologists attribute Senyar’s formation to an unusual combination of enhanced cross-equatorial flow, very warm sea-surface temperatures, and an active Madden–Julian Oscillation (MJO) phase.
A 2022 study on low-latitude vortex formation across the Maritime Continent showed that similar vortices often arise under easterly or westerly wind regimes but almost never intensify into full tropical cyclones.
Before Senyar, the only documented cyclone of this kind was Tropical Storm Vamei, which formed near 1.5° N off southern Malaysia in December 2001.
Like Vamei, Senyar was compact but well-organized, confirming that although extremely rare, equatorial tropical cyclones can occur under brief favorable conditions.
Senyar is therefore regarded as the second documented cyclone in or near the Strait of Malacca and the first on record to produce severe impacts across Indonesia, Malaysia, and southern Thailand.
References:
1 Floods and landslides in Indonesia’s Sumatra kill at least 174 – Reuters – November 28, 2025
2 MetMalaysia: Tropical Storm Senyar Weakens, Rain And Strong Winds Expected To Continue – Bernama – November 28, 2025
3 Death toll from flooding in southern Thailand reaches at least 145 – Al Jazeera – November 29, 2025
I'm a dedicated researcher, journalist, and editor at The Watchers. With over 20 years of experience in the media industry, I specialize in hard science news, focusing on extreme weather, seismic and volcanic activity, space weather, and astronomy, including near-Earth objects and planetary defense strategies. You can reach me at teo /at/ watchers.news.
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