Singapore temperatures last year match record set in 2016

Last year matched the hottest year on record in Singapore, with the annual mean temperature hitting 28.4 deg C.

In its 2019 review of Singapore's weather and climate released yesterday, the Meteorological Service Singapore (MSS) said that last year's mean temperature was the same as that in 2016, and 0.9 deg C higher than the 1981 to 2010 long-term average.

This was likely the result of a combination of global warming and the occurrence of a coupled ocean-atmosphere phenomenon called the Indian Ocean Dipole (IOD), which caused drier, warmer conditions in South-east Asia.

In its positive phase, the IOD draws rainfall away from countries on the Indian Ocean's eastern rim, including Singapore and Australia, and causes warmer temperatures in affected areas.

"The cause of the warm tem-peratures last year can be attributed to the strong positive IOD phase on top of the long-term warming trend over Singapore that is due to global warming and urbanisation," an MSS spokesman told The Straits Times.

The mean temperature from 2010 to 2019 - 27.94 deg C - in Singapore also surpassed the previous warmest decade from 2009 to 2018, which had a mean temperature of 27.89 deg C.

MSS said this trend is consistent with global temperature patterns.

The World Meteorological Organisation said on Wednesday that last year was the earth's second-hottest since records began, and that the world should brace itself for more extreme weather events such as the bush fires ravaging much of Australia.

The positive phase of the IOD - among the strongest since the 1960s - also resulted in drier than usual weather here.

Last year was the third-driest year recorded since 1869 as the strong, positive IOD event led to lower rainfall and higher temperatures, especially during the third quarter, said MSS.

The lack of rainfall contributes to higher temperatures because drier conditions imply suppressed cloud formation or a lack of it, an MSS spokesman explained. "This, in turn, allows for stronger heating of the ground and increases surface temperatures," she added.

Above average temperatures were recorded in all the months of last year, with August (29.1 deg C) and September (29.0 deg C) being the warmest on record for those two specific months.

Forest fires escalated in the region as the IOD event coincided with the south-west monsoon season, leading to drier than usual conditions. Singapore experienced haze as a result, with the 24-hour Pollutant Standards Index - a measure of air quality - peaking at an unhealthy 154 in southern Singapore on Sept 19, the highest recorded for the year.

The year 2016 had also seen a coupled ocean-atmospheric phenomenon in the Pacific Ocean, located to Singapore's east.

That year, a strong El Nino event which started in 2015 led to drier weather across the region and caused temperatures to spike.

Singapore had some respite from the haze with the arrival of the rains late last year.

As it turned out, the usually rainy phase of the north-east monsoon season also broke a record. The Republic experienced its longest north-east monsoon surge over the past decade. Rain fell consistently for about seven days in December.

The MSS said: "In the first half of December, Singapore experienced an extended period of cool, cloudy and windy conditions.

"Between Dec 9 and 15, a north-east monsoon surge brought periods of rain and showers over many parts of the island and were heavy on some occasions."

It brought about a spell of unusually cool weather.

The lowest daily minimum temperature during the period was 22 deg C on Dec 11, said MSS.

The daily maximum temperature during the monsoon surge episode ranged between 26.5 deg C and 29.9 deg C on almost all days, it added.