The National Environment Agency’s 24-hour PSI for central Singapore was 102 at 6am on Sunday, 4 October 2026, in the unhealthy range, after sitting between 101 and 105 from 11am to 10pm on Saturday.
Elsewhere at 6am, readings were 91 in the east, 87 in the west, 82 in the south and 77 in the north. One-hour PM2.5 readings at 6am were between 28 and 50 µg/m³, in the normal band across all five regions.
At 5pm on Saturday, the 24-hour PSI ranged from 79 to 104 across the island, and one-hour PM2.5 concentrations were between 30 and 56 µg/m³, straddling the normal and elevated bands.
What is driving the haze
Moderate to dense smoke plumes from southern Sumatra were drifting towards Singapore and the surrounding region on Saturday, 3 October, and smoke haze from fires in Kalimantan was also observed.
Across the region, moderate transboundary smoke haze covered parts of Peninsular Malaysia, Singapore and southern and central Sumatra on Saturday, while moderate to dense plumes hung over many parts of Kalimantan and Sarawak. Thick smoke haze and cloud cover hid the full extent of the hotspots. The ASEAN Specialised Meteorological Centre expects strong El Niño conditions and below-normal rainfall over much of the region from September to November, which raises the risk of prolonged dry spells and transboundary haze. More showers as the Southwest Monsoon gives way to the inter-monsoon period in October could bring some relief.
Sunday forecast and health advisory
NEA’s 5pm update on Saturday forecast Sunday’s 24-hour PSI in the high-moderate to low-unhealthy range. Dry weather is expected to persist over Singapore and the surrounding region, and the prevailing southeasterly or southwesterly winds are expected to strengthen, so smoke haze remains a risk.
Under NEA’s health advisory, a 24-hour PSI in the unhealthy band of 101 to 200 means healthy people should reduce prolonged or strenuous outdoor physical exertion. The elderly, pregnant women and children should minimise it, and people with chronic lung or heart disease should avoid it. At moderate levels of 51 to 100, all groups can carry on as normal. For activities in the next hour, the advisory goes by the one-hour PM2.5 reading instead: activity is normal in Band 1 (up to 55 µg/m³), while in Band 2 (56 to 150 µg/m³) healthy people should cut down on strenuous outdoor activity for the next hour and the elderly, pregnant women, children and people with chronic lung or heart disease should avoid it.
