Rain in the past few days helped to ease hazy conditions in Singapore, with the air quality in the moderate range as of 7pm yesterday.
Despite the haze that blanketed South Sumatra's provincial capital of Palembang on Wednesday, the rain has helped maintain air quality here, said Dr Erik Velasco, a research scientist from the Singapore-MIT Alliance for Research and Technology.
"The winds have been blowing from the south-south-east direction. If the winds switch a little bit to the west and the fires continue in Sumatra, we could expect a more intense smoke-haze.
"Fortunately, we have experienced some rain that has helped to maintain the air quality at moderate levels," he said.
As at 7pm yesterday, the National Environment Agency (NEA) said the 24-hour Pollutant Standards Index (PSI) was in the moderate range, hovering between 64 and 70. Under such conditions, normal activities can be carried out.
Two hot spots were detected in Sumatra yesterday, said NEA, with smoke plumes and haze visible in the southern half of the Indonesian island.
For today, the weather agency expects thundery showers in the late morning and early afternoon. But occasional slight haze from Sumatra might be on the cards this afternoon, if the winds shift briefly to blow from the south, it added. Overall, air quality for the next 24 hours is expected to be in the moderate range.
Dr Velasco said the frequent rain last week had lessened the impact of the fires in Indonesia.
"Two weeks ago, a massive number of hot spots were detected in Kalimantan, but the PSI rose only to moderate levels."
Noting that weather forecasts for Riau, Indonesia, showed "weak possibilities of rain", he said: "We should cross our fingers for rain in the whole region - in Singapore and Malaysia, to attenuate the smoke-haze impact, and in Indonesia, to stop the fires."
The severe smoke-haze that Singapore experienced in 2013 was triggered by two months of dry weather in the region.
The PSI had then reached hazardous levels.
But associate professor Richard Webster from Nanyang Technological University's School of Physical and Mathematical Sciences warned that if the levels of fires and wind conditions are similar to 2013, PSI readings could be just as bad for short periods.
"Because this year is an El Nino year, some have predicted that the haze could be particularly bad due to warmer temperatures, although this appears not to have occurred so far," he said.