Singapore may see haze return with the number of hotspots surging to 488 in neighboring Indonesia's Sumatra, the city-state's National Environment Agency (NEA) released the data on Monday.
As of 10: p.m., the three-hour Pollutant Standards Index reading stood at 24, remaining in the good range.
The number of hotspots increased nearly six-fold from 86 on Saturday to 488, of which 267 are in Riau province and 66 in South Sumatra, the NEA said.
Moderate to dense smoke plumes emanating from some of the hotspots in central Sumatra were also observed.
The CEO of the NEA has addressed the city-state's "concerns over the sharp increase in hotspot counts in Sumatra, particularly over the past few days."
The NEA said considering the dry weather conditions in central and southern Sumatra for the next few days, as well as the change of the wind's direction, "there is a possibility that Singapore could experience slightly hazy conditions."