START OF DRY SEASON FOR THE SOUTHERN ASEAN REGION
Singapore, 29 May 2023 – The ASEAN Specialised Meteorological Centre (ASMC) has issued Alert Level 1 today, indicating the start of the dry season associated with the Southwest Monsoon in the southern ASEAN region. Persistent drier weather has been observed over most parts of Brunei, Indonesia, Malaysia, Singapore and southern Thailand in recent days, as the monsoon rain band moves north of the Equator. With a high likelihood of El Niño1 conditions developing in the coming months, the dry season is expected to be more intense and prolonged compared to recent years, and extend into October 2023.
2 Presently, hotspot activities in the southern ASEAN region are still subdued with 14 and 13 hotspots detected in the southern ASEAN region on 27 May 2023 and 28 May 2023 respectively. A few localised smoke plumes were detected in parts of the region on some days in May 2023, but no transboundary smoke haze occurrence has been observed so far.
3 Since earlier this year, warmer subsurface ocean temperatures have been observed in the eastern tropical Pacific, which is an early sign that support El Niño conditions developing in the next few months. Additionally, a positive Indian Ocean Dipole2 , which suppresses cloud formation over certain parts of the tropical Indian Ocean, may develop in the next one to two months. Both climate phenomena typically bring drier and warmer conditions to many parts of the southern ASEAN region.
4 ASMC assesses that there is a higher risk of escalated hotspot activities and transboundary smoke haze occurrence in the southern ASEAN region between June and October 2023, compared to the last three years when the dry season was moderated by prolonged La Niña conditions. Early precautionary and mitigation measures are advised to prevent the occurrence of fires and transboundary haze in the region.
5 For regular and ad-hoc updates of the regional weather and smoke haze situation and early warnings, please visit the ASMC website at http://asmc.asean.org.
 El Niño is a naturally occurring climate pattern associated with changes in both the ocean and atmosphere in the equatorial Pacific Ocean, including an abnormal warming of the surface waters in the eastern equatorial Pacific. Typically lasting 9-12 months and occurring every three to five years, it produces widespread and at times severe changes in the global climate.
 The Indian Ocean Dipole (IOD) is similar to the El Niño, but occurs in the equatorial Indian Ocean and of shorter duration, typically ending by December-January. The IOD varies between three phases – positive, negative and neutral.
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