Observed temperature trends point to a warmer future
Singapore, 23 March 2024 – Singapore’s 2023 Annual Climate Assessment Report was released by the National Environment Agency (NEA)’s Meteorological Service Singapore (MSS), in conjunction with the celebration of World Meteorological Day. The report covers Singapore’s main climatic features and notable weather records and events in 2023. The report is available on the MSS website at www.weather.gov.sg (please refer to Annex A for an infographic on Singapore’s climate in 2023).
Key Findings
Temperature
2 In 2023, Singapore’s annual average temperature was 28.2 degrees Celsius, making it the fourth warmest year on record (tied with 1997 and 2015). After a cool start to 2023, monthly temperatures from April onwards were above their respective long-term averages. Several temperature records were broken between May and November. For example, October’s monthly mean temperature of 29.0 degrees Celsius significantly exceeded the previous October record in 2002 by 0.3 degrees Celsius.
3 The last decade (2014-2023) has been Singapore’s warmest decade on record at 28.06 degrees Celsius. This is 0.33 degrees Celsius warmer than the 2004-2013 decade. However, this latest decade would be considered cooler than average as compared to mid-century (2040-2059), based on future climate projections from Singapore’s Third National Climate Change Study (V3).
4 While the long-term warming trend contributes to warmer temperatures, climate variability in 2023 also played a role. Persistent La Niña [1] conditions that developed in 2021, ended in the first quarter of 2023. El Niño conditions developed by the second half of the year. A positive Indian Ocean Dipole [2] also developed in the second half of 2023. Both El Niño and positive Indian Ocean Dipole events are typically associated with warmer temperatures in Singapore, while La Niña tends to moderate Singapore’s temperatures.
5 Singapore’s annual temperature trend in 2023 is similar to the global trend recently reported by the World Meteorological Organization [3]. With the shift to El Niño conditions, 2023 has been declared the warmest year on record globally since 1850. Since the warmest annual temperatures from any El Niño events typically occurs the year after an El Niño forms (both for Singapore and globally), 2024 could be an even warmer year.
Heat Stress
6 Singapore experienced 37 days with some period of high [4] heat stress in 2023, when the hourly average Wet Bulb Globe Temperature was equal to or greater than 33 degrees Celsius. The highest number of high heat stress days occurred in May (10 days), followed by October (eight days). Record high temperatures and lower rainfall contributed to more periods of high heat stress in these two months. V3 estimates the number of high heat stress days to triple by the middle of this century, compared to in 2023 (between 53 and 155 days, depending on the future emissions scenario).
Rainfall
7 Along with warmer temperatures, in 2023 Singapore experienced its seventh wettest year since 1980. The average annual total rainfall (2866 mm) was 13.1 per cent above the long-term 1991-2020 average of 2534mm. The first three months of the year were particularly wet, including February 2023 recording more than twice its long-term average of 132mm. There were also a number of drier than average months, including August and October, although the 2023 Southwest Monsoon season was overall wetter than usual when an El Niño is present. The V3 projections indicate that Singapore’s wet months (December - January) could get wetter, which follows what has been observed (24.1mm per decade from 1980-2023). However, while the dry months (June - September) are projected to get drier, so far this has not been observed – although this may be due to the influence of El Niño and La Niña on Singapore’s rainfall for these months.
Notable Weather Events in 2023
Rare late wet monsoon surge
8 A wet monsoon surge occurred in late February - early March 2023, an uncommon occurrence during the end phase of the Northeast Monsoon. On 28 February, heavy rains from the monsoon surge brought 225.5mm of rainfall at Kallang – the highest daily total rainfall ever recorded in February. Temperatures also dropped to 21.1 degrees Celsius at Newton, the lowest temperature recorded in 2023.
Scorching May
9 Dry and warm weather in May 2023 led to new temperature records for the month. On 13 May 2023, the highest daily maximum temperature of 37.0 degrees Celsius was recorded at Ang Mo Kio, making it not only the warmest day in May on record, but also tying with 17 April 1983 as the highest ever temperature recorded in Singapore. There were nine days in May where maximum temperatures were 35 degrees Celsius or above. At the Changi climate station, both the monthly average daily mean temperature and monthly average daily minimum temperature recorded new highs for May (29.5 degrees Celsius and 26.7 degrees Celsius respectively).
Smoke Haze in October
10 After an escalation in hotspot activity and occurrence of smoke haze in the surrounding region, a shift in the prevailing winds on 7-8 October 2023 blew lighter smoke haze to Singapore. This resulted in hazy conditions with the air quality deteriorating into the Unhealthy range over parts of the island on 7 and 8 October 2023. The highest 24-hour PSI of 123 was recorded in the eastern part of Singapore between 8pm and 9pm on 7 October 2023.
[1] La Niña and El Niño are a climate phenomenon in the tropical Pacific that affects climate around the world.
[2] The Indian Ocean Dipole (IOD) refers to a sustained change in the difference between sea surface temperatures in the tropical western and eastern Indian Ocean.
[3] World Meteorological Organization’s State of the Climate 2023 report
[4] Heat stress levels are based on Wet Bulb Globe Temperature (WBGT). Days of high heat stress are defined when any hourly average WBGT at a station is equal to or greater than 33 degrees Celsius.
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Annex A
Infographic on Singapore’s Climate in 2023
