REGIONAL SUMMARY:
During the fortieth week of 2025, a total of 20 disaster events were reported across the ASEAN region, including earthquakes, floods, landslides, and wind-related incidents affecting Cambodia, Indonesia, Lao PDR, Malaysia, and the Philippines. In Cambodia, National Committee for Disaster Management (NCDM) reported flooding in several provinces, including Ratanakkiri, Stung Treng, Kratie, Prey Veng, Kampong Thom, Siem Reap, Mondulkiri, Banteay Meanchey, Tbong Khmum, Oddar Meanchey, and Preah Vihear. In Indonesia, Badan Nasional Penanggulangan Bencana (BNPB) recorded multiple disasters across Jambi, West Java, Central Java, East Java, East Kalimantan, North Maluku, and South Sumatra. In Lao PDR, National Disaster Management Office (NDMO) reported disaster incidents associated with Tropical Cyclone BUALOI affecting Attapu, Houaphanh, Bolikhamxay, Champasak, Vientiane Capital, Vientiane Province, Savannakhet, Xayabouly, Xaisomboun, and Xiangkhouang. In Malaysia, Agensi Pengurusan Bencana Negara (NADMA) reported flooding and wind-related disasters in Perak, Kedah, Johor, and Kuala Lumpur. In the Philippines, National Disaster Risk Reduction and Management Council (NDRRMC) reported disasters in Regions I, II, III, CAR, and IVA due to the effects of Tropical Cyclone MATMO, as well as the M6.9 earthquake and subsequent landslides in Cebu. Meanwhile, in Thailand, flooding in 17 provinces first reported in Week 37 continues to be monitored by Department of Disaster Prevention and Mitigation (DDPM). In Viet Nam, Viet Nam Disaster and Dyke Management Authority (VDDMA) reported disasters associated with Tropical Cyclone BUALOI beginning at the end of Week 39.
HIGHLIGHT:
During the last week of September 2025, Tropical Cyclone BUALOI made landfall over Mainland Southeast Asia between late 28 September and early 29 September, affecting Lao PDR, Thailand, and Viet Nam. In Viet Nam, according to VDDMA, as of 5 October at 0600H UTC+7, impacts of TC BUALOI have resulted in 56 fatalities, 11 persons missing, and 172 injuries. Reports also indicated that 389 houses collapsed, 179.9K houses were damaged, and 12.3K houses flooded. Preliminary estimates place the economic losses at approximately USD 713K.
In the Philippines, NDRRMC reported that, as of 5 October at 0500H UTC+7, the impacts of TC MATMO have affected 70.6K families (225.6K persons), with 3.9K families (12K persons) displaced across 284 evacuation centres (ECs) and 2.9K families (8.6K persons) displaced outside ECs in Regions I, II, CAR, III, and CALABARZON. Reported damages include 98 road sections (27 still impassable), 34 bridges (32 still impassable), and 13 damaged houses. Additionally, a magnitude 6.9 earthquake struck Cebu, the Philippines, on 30 September at 2059H UTC+7. As of 6 October at 0500H UTC+7, NDRRMC reported that 155K families (547.4K persons) were affected, with 405 families (1.3K persons) displaced to 4 ECs, and 7.4K families (17.7K persons) displaced outside ECs. A total of 72 reported fatalities and 559 injuries are currently under validation.
The AHA Centre continues to closely monitor these situation, in coordination with the affected and potentially affected ASEAN Member States, and stands ready to provide support should the need arise.
HYDRO-METEO-CLIMATOLOGICAL:
For the past week, data from the ASEAN Specialised Meteorological Centre (ASMC) indicated medium to high 7-day average rainfall concentrated associated from the Philippines Sea going west-northwest ward to the Viet Nam associated with the development of Tropical Cyclone MATMO, in addition to Brunei Darussalam, Cambodia, Indonesia, Lao PDR, Malaysia, Myanmar, Philippines, Thailand, and Viet Nam. Brunei Darussalam, Cambodia, Indonesia, Lao PDR, Malaysia, Myanmar, the Philippines, Thailand, and Viet Nam. According to NCHMF, as of 1300H UTC+7 on 6 October, MATMO has weakened into a low-pressure area and is forecasted to move west-northwestward while gradually dissipating.
GEOPHYSICAL:
Seven (7) significant earthquakes (M>5.0) were recorded by Indonesia’s Badan Meteorologi, Klimatologi, dan Geofisika (BMKG) and the Philippines Institute of Volcanology and Seismology (PHIVOLCS). Mount Marapi (alert level II), Semeru (alert level II), Lewotobi Laki-laki (alert level III), Ili Lewotolok (alert level III), and Ibu (alert level II) in Indonesia, and Kanlaon (alert level 2), Taal (alert level 1), Mayon (alert level 1), and Bulusan (alert level 1) volcanoes in the Philippines reported recent volcanic activity according to Pusat Vulkanologi dan Mitigasi Bencana Geologi (PVMBG) and PHIVOLCS.
OUTLOOK:
According to the ASEAN Specialised Meteorological Centre (ASMC), for the coming week, wetter conditions are predicted over much of the central and southern Maritime Continent. For the regional assessment of extremes, there is a low chance of very heavy rainfall conditions across the ASEAN region; and small increase in chance for extreme heat conditions to occurs over northeast Mainland Southeast Asia. While ENSO neutral conditions have been present, models predict potential for La Niña conditions to develop in the coming months. There are also signs that a negative Indian Ocean Dipole has developed, with models predicting negative IOD conditions in October.
Sources:
ASEAN Disaster Monitoring & Response System (DMRS); ASEAN Specialised Meteorological Centre (ASMC); Joint Typhoon Warning Centre (JTWC);
Cambodia: NCDM;
Indonesia: BNPB, BMKG, PVMBG;
Lao PDR: NDMO;
Malaysia: NADMA;
Philippines: NDRRMC, PAGASA, PHIVOLCS;
Thailand: DDPM;
Viet Nam: VDDMA, NCHMF;
Various news agencies.
