Synoptic-to-interannual drivers of humid heat variability in equatorial Southeast Asia

Hidayat, Anistia M., Birch, Catherine E., Jackson, Lawrence S., Schwendike, Juliane, Sanchez, Claudio and Matthews, Adrian J. ORCID: https://orcid.org/0000-0003-0492-1168 (2026) Synoptic-to-interannual drivers of humid heat variability in equatorial Southeast Asia. npj Climate and Atmospheric Science. ISSN 2397-3722 (In Press)

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Abstract

As the Earth continues to warm, humid heat extremes (HHEs) have emerged as a widely recognised threat to human health in equatorial Southeast Asia (SEA). While most studies have focused on climate trends, this study presents a comprehensive analysis of the synoptic and large-scale drivers of HHEs. On daily timescales, both the Madden-Julian Oscillation (MJO) and Kelvin waves are the leading modes of HHE variability. HHE risk increases by 1.2–1.4x during the dry-to-wet transition of the MJO phases, predominantly driven by increased near-surface specific humidity preceding the peak rainfall anomaly in phase 2 and increased shortwave radiation due to reduced cloud cover in phase 8. HHE risk increases by 1.3–2.0x during the dry phase of equatorial Kelvin waves, which drives subsidence and increased shortwave warming. On interannual timescales, El Nino is the leading driver, under which HHE risk increases 3 – 5x. Despite the limited overlap (19%) between wet- and dry-bulb temperature extremes, the differences in their temperature and humidity conditions, and their drivers, are small. This understanding lays the groundwork for short-range to seasonal forecasts, which are a crucial component of much-needed heat early warning systems.

Item Type:	Article
Uncontrolled Keywords:	sdg 3 - good health and well-being,sdg 13 - climate action ,/dk/atira/pure/sustainabledevelopmentgoals/good_health_and_well_being
Faculty \ School:	Faculty of Science > School of Environmental Sciences University of East Anglia Research Groups/Centres > Theme - ClimateUEA
UEA Research Groups:	Faculty of Science > Research Groups > Centre for Ocean and Atmospheric Sciences
Depositing User:	LivePure Connector
Date Deposited:	11 Jun 2026 13:00
Last Modified:	18 Jun 2026 21:00
URI:	https://ueaeprints.uea.ac.uk/id/eprint/103369
DOI:

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