31 JUL 2023


Summary of the Twentieth Session of the ASEAN Climate Outlook Forum (Online, ASMC)


The 20th Session of the ASEAN Climate Outlook Forum (ASEANCOF-20) was coordinated by ASEAN Specialised Meteorological Centre (ASMC) and held online over three days in May 2023, culminating in a final webinar on 30 May with open registration. The virtual format enabled a larger audience to attend, with almost 50 participants from the ASEAN Member States National Meteorological and Hydrological Services (NMHS), experts and representatives from climate services attending the meeting over the various days.
Participants from NMHSs, WMO-RAP, ASMC, the ASEANCOF Working Group, and end-users on the last day of ASEANCOF-20.

Consensus: Rainfall
The consensus for June-July-August (JJA) 2023 outlook was achieved through an online session, which included collation of information from different NMHSs through questionnaires and discussions regarding the current climate conditions and predictions in the Southeast Asia region. In particular, ASEANCOF considered the influence of the El Niño Southern Oscillation (ENSO) and the Indian Ocean Dipole (IOD) on the climate system over Southeast Asia.

ASEANCOF-20 agreed that for the upcoming boreal (Northern Hemisphere) summer season (JJA 2023), below- to near-normal rainfall is predicted over most of the southern ASEAN region, except northeastern Borneo and eastern Maritime Continent where near- to above-normal rainfall is predicted. Over much of the northern ASEAN region, a mix of near- to above-normal rainfall is predicted. Above-normal rainfall is predicted over parts of southwestern and southeastern Mainland Southeast Asia, while near- to above-normal rainfall is predicted elsewhere over this region. Above-normal rainfall is predicted for much of the western half of the Philippines, with near- to above-normal rainfall elsewhere.

Consensus maps for probabilistic outlook on rainfall and temperature for JJA 2023

Consensus: Temperature
On temperature, ASEANCOF-20 agreed that near- to above-normal temperature is predicted over Southeast Asia. Near-normal temperature is predicted over parts of the southern Maritime Continent, including southern Sumatra and Java. Near- to above-normal temperature is predicted over the southwestern and southeastern parts of Mainland Southeast Asia, Malaysia, and the Philippines. Elsewhere in Southeast Asia, above-normal temperature is predicted.

Theme of ASEANCOF-20
The theme of ASEANCOF-20 was ‘Advances in climate services on subseasonal to seasonal timescales’. The first two days covered the development of the consensus outlook, including sharing from NMHSs and experts and updates from the Southeast Asia Regional Climate Centre – Network. An introduction to a Python based machine learning toolbox, XCAST by NOAA, for subseasonal and seasonal outlook was given on the first day of ASEANCOF. On the last day of ASEANCOF-20, a sharing session was held on the impact of El Niño on Southeast Asia, involving NMHSs and users of ASEANCOF information.

The ASEANCOF Consensus Statement for JJA 2023 can be found here.