START OF DRY SEASON IN THE SOUTHERN ASEAN REGION
Singapore, 16 July 2021 – According to the ASEAN Specialised Meteorological Centre (ASMC), the traditional dry season in the southern ASEAN region has started and is expected to extend into October 2021. The dry season is associated with the onset of the Southwest Monsoon in the region.
2 During this period, the equatorial Pacific Ocean is expected to remain in a neutral state, with no developing El Niño or La Niña. However, in the equatorial eastern Indian Ocean, waters have been gradually warming and are forecast to become warmer than normal in the following weeks. This climate phenomenon, known as the negative phase of the Indian Ocean Dipole (IOD), typically brings more rainfall to the region. For the July to October period, above average rainfall can be expected over many parts of the southern ASEAN region.
3 Recent wet weather in many parts of the southern ASEAN region has helped to subdue the development of fire hotspots in the fire-prone areas. Despite the likelihood of higher than normal rainfall in the next few months, more fire hotspots could still develop during occasional extended periods of dry and warm weather. The prevailing southwest monsoon conditions mean that low-level winds in the region blow from the southeast or southwest, and occasionally from the west. Transboundary haze may occur if the winds blow any smoke haze from fires to neighbouring countries.
4 ASMC assesses that the probability of a similar recurrence of the severe haze episodes in 2015 (El Niño year) and 2019 (positive IOD year) is low this year. Nonetheless, early precautionary and mitigation measures are advised to prevent the occurrence of 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.
 The southern ASEAN region comprises of Brunei Darussalam, Indonesia, Malaysia, Singapore and southern Thailand.