Anak Krakatau Ash: Where Will the Wind Carry It?

Anak Krakatau Ash Moves Over the Indian Ocean as Wind Patterns Shift

Tempatdonasi.com – Volcanic ash from Mount Anak Krakatau has extended beyond the volcano’s summit during the past two days, with the plume observed moving toward the south-southwest and out over the Indian Ocean. The latest observation was recorded at 4 a.m. WIB on Tuesday, September 8, 2026.

Information from the Center for Volcanology and Geological Hazard Mitigation (PVMBG), the Darwin Volcanic Ash Advisory Centre, and RGB imagery from Himawari-9 showed ash reaching about 6,000 feet in the lower atmosphere, including near-surface levels. Its movement is closely tied to changing wind conditions at different atmospheric heights around Anak Krakatau and nearby waters.

Anak Krakatau lies in the Sunda Strait, between Java and Sumatra, making wind direction an important factor in assessing where airborne ash may travel. Conditions can differ substantially between the lower, middle, and upper atmosphere, meaning the plume’s route may change as ash rises or disperses.

Dry-Season Conditions Remain in Place

Banten is expected to receive relatively limited rainfall through September and October 2026. The Regional Meteorology, Climatology, and Geophysics Agency (BMKG) for Region II projects monthly rainfall across the province at 0 to 100 millimeters during that period.

Rainfall is forecast to rise from November, with medium to high levels expected to develop and strengthen into early 2027. For local authorities, the rainfall outlook and daily wind forecasts are key references when considering public safety measures and other policy responses near the volcano’s area of influence.

Lutfi Mujahidin, head of the Banten Provincial Disaster Management Agency (BPBD), said the wind forecast for September 9 pointed away from eastern population centers.

“For example, on September 9, the wind is blowing towards the northwest, meaning that the educational process in the eastern areas such as Tangerang, Jakarta, and Bogor is safe,”

The statement reflects the importance of monitoring wind direction rather than viewing volcanic ash risk as static. Even when ash is moving away from land, authorities and residents may need to follow updated notices because atmospheric conditions can change from one day to the next.

Wind Outlook Around Anak Krakatau

On Monday, September 7, lower-level winds were generally southeasterly at 5 to 25 knots. In the middle atmosphere, winds ranged from north-northeast to southeast at 10 to 15 knots. Higher up, northeasterly winds were recorded at speeds between 5 and 50 knots.

For Tuesday, September 8, the lower atmosphere was dominated by east-southeasterly winds of 5 to 20 knots. Middle-level winds came from the northeast at 5 to 15 knots, while upper-level winds also originated from the northeast and ranged from 5 to 25 knots.

On Wednesday, September 9, east-southeasterly winds of 5 to 20 knots were expected near the lower atmosphere. The middle atmosphere was forecast to receive west-northwesterly winds at 5 to 10 knots. At upper levels, winds were expected to vary from northeast to southeast, with speeds from 5 to 45 knots.

The outlook for Thursday, September 10, showed lower atmospheric winds described as east-southwest at 2 to 20 knots. Middle-level winds were forecast from the west-northwest at 5 to 10 knots. Upper-air winds were expected from the north-southeast at 15 to 50 knots.

On Friday, September 11, lower-level winds were projected to shift from northeast to east, ranging from 2 to 15 knots. In the middle atmosphere, winds could extend from northeast to west at 5 to 10 knots. Northeasterly upper-level winds were forecast at 25 to 50 knots.

Saturday, September 12, was expected to bring northeast-to-east winds in the lower atmosphere, with speeds of 10 to 20 knots. Mid-level winds were forecast from northeast to southeast at 5 to 10 knots, while upper winds from the northeast could reach 30 to 40 knots.

For Sunday, September 13, lower atmospheric winds were forecast from east-southeast at 10 to 30 knots. The middle atmosphere was expected to see winds from northeast to southeast at 2 to 15 knots. At higher elevations, winds could move from northeast to east at 15 to 30 knots.

Why Multiple Wind Levels Matter

Wind forecasts at several altitudes help show why ash movement cannot be defined by a single direction. Ash near the surface may follow one path, while material at greater altitude can be carried elsewhere by faster or differently oriented air currents. This makes continuing observation important for aviation, maritime activity, communities near the Sunda Strait, and areas that could potentially be affected if wind patterns turn toward land.

For now, the observed plume’s south-southwest movement places it over the Indian Ocean. The coming days’ forecasts show a mix of easterly and northeasterly flows at lower and upper levels, alongside occasional west-northwesterly winds in the middle atmosphere. Those variations underline the need for daily updates as Anak Krakatau’s activity and regional weather conditions develop.