Fewer hotspots were detected in Sumatra on Wednesday, the National Environment Agency said in its haze advisory, but this could be due to cloud cover.
Satellites monitoring the fires detected 283 hotspots on Wednesday, down from 458 on Tuesday. About half were in the Riau province.
Despite the drop in the hotspot count, which is partly due to some cloud cover, more smoke plumes together with haze were visible in Riau on Wednesday, the NEA said.
The fires across Sumatra are set to clear land for farming, and have been worsened by the current dry weather.
But the likelihood of haze blanketing Singapore remains low while the wind blows from the north-east for this fortnight, the NEA added, although Singapore may experience occasional slight haze due to accumulation of particulate matter under stable atmospheric conditions.
Air quality updates are available from www.nea.gov.sg, www.haze.gov.sg, on www.facebook.com/NEASingapore or on Twitter @NEAsg.