Singapore and Malaysia may have been spared the haze in the past few days because of fewer fires in Indonesia, the National Environment Agency (NEA) said yesterday.
Weather services director Patricia Ee said the number of hot spots or fires observed in Sumatra - ground zero for the haze - fell from 42 at 4pm on Thursday to just 15 at the same time yesterday.
"It rained a bit in Sumatra. The extent of the fires may also have changed such that wind does not carry them to Singapore," she explained.
Indonesia has also carried out cloud-seeding - which artificially creates rain - and water-bombing efforts to combat the fires.
While the exact number of fires is difficult to determine because clouds may have obscured the view of the ground, NEA deputy chief executive officer Joseph Hui said the haze over Sumatra itself has "thinned".
Singapore's three-hour Pollutant Standards Index (PSI) hit a record 401 at noon on June 21, but fell sharply over last weekend. Since then, the air quality here has remained mostly in the "moderate" range, even becoming "good" for a few hours on Wednesday evening.
A PSI reading up to 50 puts it in the "good" range, while a reading between 51 and 100 puts it in the "moderate" range.
Still, the Government and experts have warned that the haze could return to Singapore before the end of Indonesia's dry season in September.
Whether the skies here remain blue or turn ashen will depend on wind directions and weather patterns, said Dr Santo Salinas, a senior research scientist at the Centre for Remote Imaging, Sensing and Processing at the National University of Singapore.
He said: "As long as there are forest fires in Sumatra, there is smoke. Singapore became less affected this past week partly because the wind changed directions.
"The probability of the haze coming back to Singapore is still quite high because it is so close to the sources of fire in Sumatra."