Review of Regional Haze Situation for March 2024

1.1 The Northeast Monsoon conditions continued over the ASEAN region in March 2024. Over areas north of the equator, the prevailing winds blew mainly from the east to northeast although light and variable winds prevailed over most parts of the Mekong sub-region. The prevailing winds over areas south of the Equator blew mostly from the west or northwest. As the Northeast monsoon conditions gradually weakened in the last week of the month, the prevailing winds over most of the ASEAN region started to turn light and variable on several days during the review period. (Figure 1).

1.2 The Mekong sub-region remained dry throughout the review period of March 2024, except for isolated shower activities in some parts of the sub-region on a few days. Elsewhere in the ASEAN region, generally wet conditions were observed in many areas, except for parts of Peninsular Malaysia, northeastern Borneo and the Philippines where there were brief periods of drier weather (Figure 1).

Figure 1: Average Daily Rainfall and Mean Winds for March 2024. (Source: JAXA GsMaP and GFS, respectively)


1.3 Over the Mekong sub-region, the hotspot counts in March 2024 were either lower or comparable to previous years (Figure 2). Over the southern ASEAN region, the hotspot counts were higher or comparable to the past few years, with an increase in Kalimantan, Peninsular Malaysia as well as Sabah and Sarawak. Kalimantan, Sabah and Sarawak recorded the highest hotspot count over 5 years (Figure 3), although the hotspot count for the southern ASEAN region during the review period remained relatively low.


Figure 2: Hotspot counts for the northern ASEAN region for March (2020-2024) based on NOAA-20 satellite surveillance.


Figure 3: Hotspot counts for the southern ASEAN region for March (2020-2024) based on NOAA-20 satellite surveillance.


1.4 Scattered to widespread hotspots were detected over many areas of the Mekong sub-region in March, with more intense and persistent clusters of hotspots in eastern Myanmar, Lao PDR, northern Thailand, and northeastern Cambodia. (Figure 4 and 5). Widespread transboundary moderate to dense smoke haze was observed mainly in the vicinity of the hotspot clusters in eastern Myanmar, northern and central Thailand, Lao PDR, as well as northern Cambodia and northern Viet Nam (Figure 6 and 7) on many days. With the deteriorating hotspots and haze situation, Alert Level 3 was issued for the Mekong sub-region on 6 Mar 2024. For the southern ASEAN region, localised moderate smoke plumes were also observed emanating from a few hotspots in eastern Peninsular Malaysia on some days during brief dry periods.


Figure 4: Distribution of hotspots detected in March 2024 based on NOAA-20 satellite surveillance.


Figure 5: Maximum fire intensity in March 2024 based on NOAA-20 satellite surveillance.


Figure 6: Number of days with moderate to dense smoke haze observed in March 2024 based on satellite imagery, ground observations, and air quality reports.


Figure 7: Moderate to dense transboundary smoke plumes were observed drifting in an easterly direction across eastern and southern Myanmar, the northern parts of Lao PDF, as well as northern and western Thailand on 31st March 2024. (Source: NOAA 20 satellite surveillance)