SINGAPORE — 2021 was Singapore's second-wettest year since rainfall data collection began in 1980, with the islandwide average eclipsed only by 2007's figure.
The Meteorological Service Singapore (MSS) said in a media release on Friday (28 January) that last year saw significantly wetter-than-average conditions, with an average rainfall of 3,167.7 millimetres across islandwide climate stations with long-term records.
This is 25 per cent higher than the annual average of 2,534.4mm, and is eclipsed only by 2007's record of 3,266.1mm.
"Most months in 2021 experienced above-average rainfall. Based on the islandwide average, almost all of these wetter months also rank within the top 10 wettest for the respective months over the past 40 years," said MSS.
January, August stood out in high rainfall
January (480.5mm) and August (426.2mm) stood out for high rainfall. Both saw at least twice their respective long term monthly averages, resulting in the wettest January and August of the past 40 years.
The first half of January 2021 brought exceptionally wet and cool weather due to the occurrence of a Northeast Monsoon surge. The monsoon surge brought continuous widespread rain, with the highest daily total rainfall of 210.6 mm recorded at the Changi climate station on 2 January.
The monthly rainfall recorded at the Changi climate station for January 2021 was 692.8mm, making it the second wettest January since rainfall records began in 1869.
August last year was unusually wet, with well-above-average rainfall recorded across the entire of Singapore. There were two days with exceptionally heavy rain that led to flash floods in some areas: 20 August, when several areas including Hougang, Choa Chu Kang, Pasir Ris and Ang Mo Kio recorded more than 100mm of rainfall; and 24 August, when heavy thundery showers fell over the entire island in pre-dawn hours.
The rainfall station at Mandai recorded a remarkable daily total rainfall of 247.2 mm on 24 August, setting a record for the highest daily total rainfall for August. It was also the wettest day of 2021.
In contrast, February 2021 was the second-driest February on record after 2014, with Changi climate station recording a mere 1.0mm of rainfall for the entire month.
Joint-10th warmest year on record
The last 10 years from 2012 to 2021 have been the warmest decade on record. The mean temperature from 2012 to 2021 was 27.97°C, 0.02°C higher than the previous record of 27.95°C for the decade from 2010 to 2019.
The annual mean temperature in 2021 was 27.9°C, which is 0.1°C above the long-term average of 27.8°C and the joint-10th warmest year on record (tied with 2018, 2014, 2009 and 2004).
While no long-term monthly temperature records were broken in 2021, December's monthly mean temperature of 27.7°C is the joint-warmest December (together with December 2015) since temperature records started in 1929.
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