Review of Regional Haze Situation for August 2021
1.1 With the low-level winds blowing from the southeast or southwest on most days, Southwest Monsoon conditions continued to prevail over the ASEAN region in August 2021 (Figure 1). The first week of August was relatively dry for most parts of the southern ASEAN region, with the monsoon rain band located north of the Equator. In subsequent weeks, the movement of the monsoon rain band closer to the Equator brought wet weather to much of the ASEAN region except its southernmost regions (Java, the Lesser Sunda Islands and southern Sumatra).
1.2 For the August 2021 review period, the hotspot counts over the southern ASEAN region were much lower than those detected in previous years (Figure 2). The hotspot counts over the northern ASEAN region were similar to those detected in previous years, with the exception of Thailand and Viet Nam which recorded higher hotspot counts (Figure 3).
1.3 Isolated to scattered hotspots continued to be detected in most parts of the southern ASEAN region in August 2021 (Figures 4 and 5). There was increased hotspot activity in areas where drier conditions were experienced, such as over the southern ASEAN region in the first week of August, and throughout the month in Java and the Lesser Sunda Islands. At times this month, localised smoke plumes were observed emanating from clusters of hotspots in Sumatra and Kalimantan. This was particularly so for West Kalimantan, where a persistent cluster of hotspots was observed on most days this month (Figure 5).
1.4 Isolated hotspots were detected mainly in the southeastern parts of the northern ASEAN region in August 2021. Towards the middle of the month, localised smoke plumes were observed in parts of central Viet Nam; no smoke plumes were observed elsewhere in the northern ASEAN region (Figures 4 and 5).