Windstorm Hazard Index Development for Malaysia

Abstract. These Windstorms in Peninsular Malaysia have increased in frequency and severity, posing growing risks to communities, infrastructure, and the national economy. Despite these escalating threats, the region currently lacks a comprehensive, location-specific index capable of evaluating and categorizing windstorm hazards for effective planning and mitigation. This study develops a Windstorm Hazard Index (WHI) to Peninsular Malaysia to assess spatial patterns of windstorm risk and support evidence-based decision-making. Four objectives were addressed: (1) identifying key environmental and geographical factors influencing windstorm occurrences; (2) quantifying these parameters using windstorm records from 2008–2018, numerical simulations generated via WRF-ARW, and urban morphology modelling using Envi-MET; (3) formulating the WHI through the integration of Analytic Hierarchy Process (AHP) and Principal Component Analysis (PCA); and (4) validating the index using documented windstorm events from 2020–2024.The WHI categorizes the peninsula into six hazard levels ranging from very low (0.1–0.5) to extreme (0.901–1.0). Southern and central states, including Negeri Sembilan and Pahang, generally exhibited very low hazard levels, while Kelantan and Terengganu showed moderate risk. High-risk zones were concentrated in northern and coastal regions such as Penang, Kedah, and Perlis, with extreme-risk areas detected in parts of Kedah and Perlis. Results indicate that wind speed, temperature, humidity, precipitation, land use, and urban density strongly influence windstorm intensity, particularly in coastal and densely built environments. Validation confirmed the WHI’s reliability, as extreme-risk classifications aligned with recorded damage patterns. Overall, the WHI serves robust framework for regional hazard assessment and disaster-resilient infrastructure development across Peninsular Malaysia.