SINGAPORE - The weather in Singapore is expected to remain dry and warm for the rest of September, the National Environment Agency (NEA) said on Monday (Sept 16), even as hazy conditions may persist.

The agency added that rainfall for September could be lower than normal, which means Singapore might enter into a rainfall deficit situation - the first time in about five years.

Dry air from high-pressure systems over northern Australia is forecast to continue blowing over to the southern South-east Asia region, including Singapore.

Cool sea surface temperatures persisting over the tropical eastern Indian Ocean will also suppress rain cloud formation over the surrounding region.

The prevailing dry weather over southern South-east Asia is expected to continue for the coming fortnight as hot spots with smoke plumes are still observed in Sumatra and Kalimantan in Indonesia.

In the light of this, NEA said Singapore may continue to experience hazy conditions during the fortnight, depending on wind conditions and the proximity and extent of the fires.

As the monsoon rain band is expected to remain over northern South-east Asia, away from Singapore, the current dry weather is expected to continue into the second fortnight of the month.

Rainfall for September here is likely to be below normal, making it the third consecutive month, after July and August, in which the monthly rainfall is more than 40 per cent below normal.

This could give rise to a potential rainfall deficit situation here, said NEA.

The total rainfall recorded for July was 51 per cent below normal, and it was 82 per cent below normal for August.

The last time a rainfall deficit occurred in Singapore was in 2014, when the average rainfall was 67 per cent, 89 per cent and 50 per cent below normal for January, February and March respectively that year.

Singapore also experienced a dry spell in August this year, with rainfall significantly below normal.

The last recorded dry spell in Singapore was in 2014, and it lasted 27 days from Feb 17 to March 15 that year.

A dry spell is defined as a period of at least 15 consecutive days with daily total rainfall of less than 1mm.

But there could be some respite in the last week of September.

NEA said that there could be short-duration showers in the afternoon on a few days then, as the high-pressure system over northern Australia is expected to weaken.

For the rest of September, the daily temperature is expected to range between 26 deg C and 34 deg C on most days, with night temperatures expected to be warm at a minimum of 27 deg C.

As for the first half of September, the weather here was generally dry and warm.

However, there were a few days when brief showers fell over Singapore.

In particular, on Sept 4, the thundery showers over many parts of the island were due to a convergence of winds over Singapore and surrounding areas.

Rainfall was heaviest over the western part of the island, and the highest daily total rainfall recorded that day was 93.3mm in Jurong West.

In the second week of September, smoke haze from hot spots in central and southern Sumatra was blown in by the prevailing winds to Singapore.

This brought slightly hazy conditions to the island, with the air quality in the high end of the moderate range on most days of the week.

But the haze situation worsened last Saturday, and caused the 24-hour Pollutant Standards Index to dip into the unhealthy range.