SINGAPORE, Oct 20 — Singapore has now enjoyed three days of better air quality, after a stretch of unhealthy-to-very unhealthy 24-hour Pollutant Standards Index (PSI) and high-to-very high hourly PM2.5, which began on October 5.

But, as the National Environment Agency (NEA) has been cautioning since October 18, winds could again turn — this time, not in the city state's favour.

In its daily haze situation update tonight, the agency said that showers are forecast over Singapore and the surrounding region tomorrow.

However, it cautioned that smoke haze from fires in Kalimantan may move towards Singapore as the winds are expected to blow from the east-southeast to southeast. 

In updates on Sunday and Monday evening, NEA warned that this could happen from as early as tonight.

In addition, dry conditions are likely to persist over southern parts of Kalimantan over the coming days. 

"Under prevailing east-southeasterly to south-easterly winds, smoke haze may drift from fires in Kalimantan towards Singapore," NEA said, adding that Singapore's 24-hour PSI is forecast to be between 110 and 180 — in the unhealthy range.

At 8pm today, hourly PM2.5 was in the normal band (0 to 55µg/m3) in northern (32), southern (46) and eastern (54) Singapore, but in the elevated band (56 to 150µg/m3) in the central (80) and western (93) regions. 

Meanwhile, PSI is in the unhealthy range (101 to 200) in western (141), central (122), eastern (106) and southern (103) Singapore, with only the northern region registering a good-to-moderate reading of 85.

Members of the public are reminded to check the latest PM2.5 reading before participating in any outdoor activities. — AsiaOne