2017 is the warmest year on record not influenced by an El Niño event
Singapore, 11 January 2018 – A review of the weather and climate in 2017 was released today by the Meteorological Service Singapore (MSS). It summarises the main climatic features and notable weather events that affected Singapore and is a prelude to the comprehensive Annual Climate Assessment Report which will be released on World Meteorological Day in March 2018. The review is available on MSS’ website at www.weather.gov.sg (refer to Annex A for an infographic on Singapore’s Climate in 2017).
2 2017 is the warmest year on record that was not influenced by an El Niño event, indicative of the long-term temperature rise that Singapore has been experiencing due to factors such as global warming and urbanisation. After two successive record warm years in 2015 and 2016, the 2017 mean annual temperature at 27.7°C has returned to a level closer to the 1981-2010 long-term average. This is still 0.2°C warmer than the long-term average and the joint 12th warmest year on record since Singapore temperature records started in 1929.
Neutral El Niño Southern Oscillation
3 The El Niño Southern Oscillation (ENSO), a naturally occurring phenomena and a major contributor to year-to-year rainfall and temperature variations over Singapore and Southeast Asia, was neutral throughout 2017 (except in November and December where it reached borderline La Niña values). Given the influence ENSO can have on temperatures, it is not surprising that following 2015’s large El Niño event which contributed to 2015 and 2016 being successive record warm years, no temperature record was broken in 2017.
4 There was a mixture of above and below normal level rainfall for the individual months in 2017, but overall the annual total rainfall was close to normal. This is more likely to be observed during a largely neutral ENSO year. The annual total rainfall of 2,045.6mm recorded was around 6 per cent below the long-term average of 2,165.9mm.
Notable weather events in 2017
5 While 2017 was not an El Niño year, some very warm days were experienced in certain months. October 2017 in particular was warm, with temperatures soaring to above 35°C on some days. Based on the Changi climate station, the hottest day in 2017 was on 18 October 2017 with a high of 34.6°C. The normally cool months of January and December also saw warmer than usual temperatures on some days.
6 Heavy rains from intense thunderstorms caused several incidents of flash floods during the year. There were also occasional incidents of fallen trees and branches due to strong wind gusts from Sumatra squalls, and there was a high frequency of these squalls in 2017. On 18 June 2017, a waterspout associated with thunderstorm clouds was observed off Singapore’s southern coast.
7 Northeast Monsoon rains contributed to a wet February and December in 2017. The 15 rain days recorded in February 2017 was almost twice the long-term average for February, a normally dry month. The year ended on a wet note as the island experienced widespread intermittent rain from a monsoon surge and a nearby vortex in the South China Sea. High rainfall on the last two days of December 2017 raised the month’s total rainfall to 371.2mm (17 per cent above the long-term average), making December the wettest month of 2017.
 El Niño Southern Oscillation (ENSO) is a recurring climate pattern caused by interactions between the atmosphere and the ocean in the tropical Pacific. During El Niño, the central-eastern equatorial Pacific Ocean is warmer than usual, leading to drier and warmer conditions especially during the June to October period over Southeast Asia. During La Niña, the central-eastern equatorial Pacific is cooler than average and the atmosphere over the Southeast Asia region is typically wetter than average. El Niño or La Niña events occur on average once every three to five years.
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