Record wet March in S’pore last year due to monsoon surge; June, November the warmest months
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Overall, 2025 was off to an exceptionally wet start due to a series of monsoon surges in January and March.
ST PHOTO: BRIAN TEO
- Singapore experienced its wettest March in 2025 due to an unusual monsoon surge, with rainfall 130% above the norm, according to the MSS report.
- The report also highlighted record-breaking rainfall in January and the impact of La Nina, contributing to Singapore's seventh wettest year since 1980.
- Despite the wet conditions, 2025 was Singapore's eighth warmest year, with record high temperatures in June and November.
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SINGAPORE - Typically one of Singapore’s drier months, March 2025 broke records as being the country’s wettest March due to an unusual monsoon surge.
The event, which lasted from March 19 to 20
In its annual climate and weather report for 2025, MSS noted that the islandwide average rainfall over the two days was 272.3mm. This exceeded the month’s long-term average of 209.7mm.
The average rainfall in March 2025 was 130 per cent above the norm, at 482.9mm, added the weatherman.
Notable monsoon surges
Overall, 2025 got off to an exceptionally wet start due to a series of monsoon surges – a weather phenomenon that brings rain and cooler weather to the country – in January and March. Downpours in both months due to three monsoon surge events made 2025 the seventh-wettest year for Singapore since 1980, said MSS.
Monsoon surges occur when bursts of cold, dry air from wintry regions like Central Asia move over the warm waters of the South China Sea, picking up moisture. This brings extensive rainfall, strong winds and cooler temperatures to Singapore.
At times, near Singapore, the winds may interact with a separate whirlpool of air, where winds are forced to move upwards, forming clouds. This is called a low-pressure vortex, which worsens the deluge over the country.
While it is common for such surges to occur in December and January during the wet phase of the north-east monsoon, the March surge was unusual as it happened during the dry phase of the monsoon season.
The dry phase of the monsoon season is called such as the rain band shifts away from Singapore.
Asked about possible reasons for the unusual monsoon surge event then, an MSS spokesperson told The Straits Times that the rain band had remained close to Singapore last March.
“At the same time, other key features of a strong monsoon surge were present, (including) the presence of a vortex near Singapore,” added the spokesperson.
The first monsoon surge of the year between Jan 10 and 13 also broke rainfall records for the month of January, MSS said in the report, which summarised key weather data in 2025.
The month’s highest-ever daily rainfall of 241.8mm was recorded on Pulau Tekong on Jan 10. This surpassed the previous high of 238.2mm recorded on Jan 30, 2011, on Pulau Ubin.
The non-stop rain over Singapore on Jan 10, 2025, coincided with high tides that resulted in flooding in some coastal areas in the low-lying East Coast area. For instance, a nearly three-hour flood was recorded
The four-day downpour last January also delayed and diverted flights, and affected businesses.
La Nina conditions
Apart from the rain brought about by monsoon surges at the start of 2025, Singapore also experienced the effects of a different climate phenomenon, La Nina, during that period.
La Nina events, caused by changes in sea surface temperatures and atmospheric pressure across the Pacific Ocean, bring cooler and wetter weather to the Republic and South-east Asia.
MSS said the short-lived La Nina climate phenomenon at the start of 2025 moderated Singapore’s temperatures in the first half of the year.
From May to August, monthly rainfall was closer to the respective long-term averages, MSS said.
But wetter conditions were also registered in Singapore from September onwards, about 40 per cent above the month’s long-term average.
La Nina conditions emerged again towards the end of 2025, coinciding with another rain-bearing phenomenon
Overall, Singapore’s average total rainfall for 2025 was more than 2,900mm – 18 per cent above the long-term average of 2,534mm.
Hottest June and November on record
Temperature records were also broken in 2025, the MSS report showed, with the year yielding the hottest June and November on record.
June was the year’s warmest month, tied with that of 1997. In both years, the average temperature in June reached a high of 29.3 deg C. The sixth month of the year also marks the start of the dry south-west monsoon season, which lasts till September.
In October and November, Singapore experienced inter-monsoon conditions, where winds are usually light and weak. During this period, hot afternoons and warm nights are common.
November’s average temperature was 28.2 deg C, up from the previous record of 28 deg C in 1998, 2015 and 2019.
Despite the rainy, cool weather in Singapore at the beginning and end of 2025, the year still marked the Republic’s eighth-warmest year on record, with a mean temperature of 28.1 deg C, tying with 2010 and 2002.
The years 2024, 2019 and 2016 are the joint warmest years in Singapore since record-keeping began in 1929, with mean temperatures of 28.4 deg C.
MSS also noted that Singapore experienced 29 days of high heat stress in 2025, compared with 21 days in 2024.
This increase was due to the set-up of more sensors islandwide that measure heat stress, said MSS.
Heat stress is measured by the wet bulb globe temperature (WBGT), which takes into account air temperature, humidity levels, wind speed and solar radiation.
High heat stress is felt when the WBGT hits 33 deg C. Those engaging in outdoor activities are urged to take longer breaks indoors, minimise exertion and drink more fluids, among other precautions.
Singapore’s highest WBGT in 2025 was 35 deg C, recorded at Sentosa Palawan Green on Oct 31.
