The National Disaster Risk Reduction and Management Council (NDRRMC) issued a clarification regarding social media posts claiming that the Sierra Madre mountain range shields Luzon from tropical cyclones.
Many Filipinos shared appreciation posts for the country’s longest mountain range as Typhoon Uwan (international name: Fung-Wong) passed through Northern and Central Luzon as a super typhoon on Sunday, November 9.
They credited the Sierra Madre for weakening “Uwan” and stressed the importance of protecting it from activities such as mining, illegal logging, quarrying, and urban expansion.
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While the Sierra Madre does act as a barrier against tropical cyclones, the NDRRMC emphasized that it does not provide complete protection from their effects.
The agency acknowledged that the mountain range can slightly weaken or slow down strong winds, particularly in the northeastern part of the region.
The NDRRMC cited a 2023 study by Dr. Gerry Bagtasa and Dr. Bernard Alan Racoma, which found that the Sierra Madre cannot guarantee full protection from weather disturbances.
It’s the time of the year to repost this https://t.co/GDcQnZjFLO https://t.co/4hr7xiZTXQ
— WeatherManila (@Weather_Manila) November 10, 2025
The study found that the strength of a tropical cyclone does not significantly decrease during the first six hours after landfall, even in the presence of mountain ranges. While the Sierra Madre can reduce a storm’s wind strength by roughly 1–13%, it also increases rainfall on its western side, including Metro Manila — by 23–55%.
However, the mountain range effectively lessens both wind and rainfall in Cagayan Valley, serving as a natural “shield” for that part of Luzon.
The researchers also noted that the Cordillera Mountain Range has a greater effect in weakening a storm’s wind strength compared to the Sierra Madre.
“Higit sa lahat, binibigyang-diin ng pananaliksik na higit na mahalagang protektahan ang Sierra Madre laban sa pagkakalbo, pagmimina, at iba pang mapanirang gawain sapagkat ito ay tahanan ng mayamang biodiversity at likas na yaman ng bansa,” the NDRRMC said.
American storm chaser Josh Morgerman, also known as “iCyclone,” likewise clarified that the Sierra Madre does not fully shield Luzon from tropical storms.
“The Sierra Madre chain weakens typhoons after they make landfall on the east coast of Luzon. These mountains do not protect the east coast of Luzon, which regularly experiences some of the strongest tropical cyclone impacts in the world,” he wrote on Facebook.
Morgerman was among the storm chasers who travelled to the Philippines to witness and monitor Typhoon Uwan in its peak intensity.
RELATED: ‘Scariest moment of my life’: Foreign storm chasers document ‘Uwan’s’ fury
Meanwhile, the tropical cyclone wreaked havoc in Northern and Central Luzon, including Metro Manila, affecting infrastructure, triggering power outages and causing widespread severe flooding in several areas.
Uwan has killed two people and displaced nearly 500,000 residents. It is the second tropical cyclone to hit the Philippines in November and the 21st for the year.
