Review of Regional Haze Situation for October 2021
1.1 Southwest Monsoon conditions transitioned to the inter-monsoon in mid-October 2021 as the winds over most parts of the ASEAN region turned light and variable (Figure 1). In the first half of October 2021, Tropical Storm Lionrock and Typhoon Kompasu contributed to increased rainfall over the northern parts of the Philippines and central parts of Viet Nam. In particular, Typhoon Kompasu caused significant damage and casualties in the Philippines due to landslides and flash floods. The southern ASEAN region experienced continued shower activities during the review period and Alert Level 0 was issued for the region on 18 October 2021, signaling the end of its traditional dry season. Average daily rainfall was relatively higher in western Kalimantan and northern Sumatra, while persistent dry conditions were observed over eastern Java and the Lesser Sunda Islands.
1.2 In October 2021, overall hotspot activity in the ASEAN region was subdued, contributed by wet weather conditions. While most of the hotspots in the southern ASEAN region were detected in Kalimantan, the number of hotspots for the southern ASEAN region were lower or comparable to previous years’ counts (Figure 2), except for Sabah and Sarawak where it was slightly higher. For the northern ASEAN region, most of the hotspots were detected in Viet Nam. The number of hotspots detected in the northern ASEAN region were also lower or comparable to previous years (Figure 3).
1.3 For the October 2021 review period, isolated to scattered hotspots were detected mainly in central Viet Nam, Borneo, and Sumatra (Figure 4 and 5). On a few days, short-lived localized smoke haze was observed to emanate from clusters of hotspots in central Kalimantan. There was no transboundary smoke haze observed over the ASEAN region during the review period.