Southeast Asia Weather & Natural Hazards Today: Wednesday, October 21, 2026

Oct 21, 2026 · @Paul

By Paul Harrison, Orbis Weather

Super Typhoon Rosal (international name Champi) is the main threat to Southeast Asia on Wednesday, October 21. The Philippine weather agency PAGASA forecasts no landfall, but expects the storm’s closest approach to Extreme Northern Luzon on Thursday and Friday, and has raised Wind Signal No. 1 in parts of northern Luzon and Catanduanes. Smoke haze from fires in Indonesia keeps air quality unhealthy across much of Peninsular Malaysia and parts of Singapore. Heavy rain threatens flash floods in Thailand through the weekend.

No other tropical cyclone is active in the western Pacific, the South China Sea, the Bay of Bengal or the Andaman Sea. This report is current to about 6:30 a.m. Wednesday in Bangkok, Hanoi and Jakarta (UTC+7), 7:30 a.m. in Manila, Singapore and Kuala Lumpur (UTC+8), and 7:30 p.m. Tuesday, October 20, US Eastern time (EDT).

Key facts

Tropical cyclones

Rosal is the only tropical cyclone in the region, and no agency forecasts landfall.

PAGASA’s 11 p.m. bulletin on October 20 forecast Rosal to pass 485 km east of Basco, Batanes, by 8 a.m. Thursday (Manila time), then turn north. It expects the storm to start weakening on Thursday and to leave the Philippine Area of Responsibility (PAR) on Friday evening or early Saturday. JTWC’s track also turns north after about three days, near 23°N, 125°E.

PAGASA forecast waves of up to 6.0 m off Batanes, Isabela and eastern Cagayan, and told mariners to stay in port.

Floods and heavy rain

Thailand

The Thai Meteorological Department (TMD) warned on October 20 that heavy, accumulated rain could cause flash floods, runoff and landslides from October 21 to 25. Its Advisory No. 8 forecasts continuous rain in the South and more rain in the lower Northeast, the East and the lower Central region, including Bangkok.

For the 24 hours to 6 p.m. Wednesday (Thai time), TMD lists isolated heavy rain in four eastern provinces, including Chon Buri and Rayong, and in most southern provinces, including Phuket and Songkhla. Waves may exceed 3 m in thunderstorms over the Andaman Sea and the Gulf of Thailand.

The Department of Disaster Prevention and Mitigation (DDPM) placed Bangkok and 35 provinces on flood alert for October 18 to 25. Floods since September 16 had killed 71 people and affected about 908,000 households in 51 provinces as of October 12, according to Reuters, as cited by Malay Mail on October 18.

Country-by-country weather today

Earthquakes

The US Geological Survey (USGS) recorded 10 earthquakes of magnitude 4.4 or more in the region in the 48 hours to the evening of October 20 (UTC). The largest and most recent are below.

Tsunami status: USGS flagged no tsunami for any of these events.

Volcanoes

Indonesia uses a four-level alert scale (1 to 4); the Philippines uses a six-level scale (0 to 5).

Marapi, Dukono, Karangetang and Lewotolok were at Level 2 in the Smithsonian report for October 8 to 14.

Haze, fires and air quality

The ASEAN Specialised Meteorological Centre (ASMC) has Alert Level 3 in force for the southern ASEAN region. It reports widespread hotspots (likely fires seen by satellite) in Kalimantan and Sumatra. High-confidence hotspots in Central Kalimantan rose from 157 on October 18 to 937 on October 19, according to BMKG figures cited by CNBC Indonesia.

In Malaysia, 25 areas had an “unhealthy” Air Pollutant Index (API, 101 to 200) at 4 p.m. on October 20 (Malaysia time), with Batu Muda in Kuala Lumpur highest at 173 (Malay Mail). Schools in six states, Kuala Lumpur and Putrajaya open on October 21, but outdoor activities stop wherever the API exceeds 100. In Singapore, the 24-hour Pollutant Standards Index (PSI) was 88 to 114 (moderate to unhealthy) at 6 p.m. on October 19, and NEA forecast 90 to 160 for October 20. Singapore has issued preventive notices to 10 Indonesian companies under its Transboundary Haze Pollution Act, AP reported.

What to watch over the next few days

• Rosal near Batanes, Thursday to Friday: PAGASA says Signal No. 2 or 3 may be raised, and strong to gale-force gusts are forecast over most of Luzon and the Visayas on Thursday. The storm is due to leave the PAR by early Saturday.
• Thailand’s wettest days: Malay Mail reported that Chon Buri and Rayong could see very heavy rain on October 21 and 22, with intense downpours in Phuket, Phang Nga and Krabi later in the week.
• Haze shifting with the wind: NEA expects winds to turn east-southeasterly through Thursday, which may carry smoke from Kalimantan toward Singapore.
• Semeru and Ibu: both have erupted repeatedly this week; PVMBG warns of possible pyroclastic flows and lahars (volcanic mudflows) up to 17 km from Semeru’s summit.

About this article

This article summarises official bulletins and news reports; it is not an official warning. For decisions about safety or travel, follow PAGASA, TMD, MetMalaysia, NEA, BMKG and local authorities. Figures carry the time and agency that issued them. Knots were converted at 1 knot = 1.852 km/h. Earthquake magnitudes are preliminary USGS values and may be revised.

Frequently asked questions

Will Super Typhoon Rosal make landfall in the Philippines? PAGASA’s forecast track keeps the centre over the sea east and northeast of Batanes. Its winds and waves can still reach land, which is why wind signals are up.

Why do Rosal’s wind speeds differ between agencies? PAGASA and JMA average winds over 10 minutes, while JTWC uses 1 minute, which gives higher numbers for the same storm. Bulletins are also issued at different times, so positions and strengths reflect different moments.

What is causing the haze? ASMC and BMKG link the smoke to land and forest fires in Kalimantan and Sumatra during a dry season that BMKG links to a very strong El Niño. Wind direction decides whether the smoke reaches Malaysia and Singapore on a given day.

When might the haze ease? ASMC says more showers from the inter-monsoon period toward the end of October could start to reduce hotspots and smoke. Until then, it expects the haze risk to stay high in areas with prolonged dry weather.