About the El Niño Heat Mortality Tracker

The El Niño Heat Mortality Tracker shows where El Niño’s heat poses the greatest threat to human life. By offering state/provincial-level data across the globe, it gives funders, policymakers, and practitioners the latest information on the most impacted regions, allowing them to prioritize where resources are most needed and where immediate action can save lives.

Key Stats

Over the next six months (October-March), the latest data projects:

About 857,000 total deaths could result from El Niño’s extreme heat, with about 373,000 of those deaths projected to occur in the next six months.
Nigeria is forecasted to experience the highest toll from El Niño’s heat, with about 56,000 deaths projected spread across the six-month forecast period.
India follows very closely, with about 55,000 heat-related deaths projected, most of them in March.
Southeast Asia remains a major hotspot, with Indonesia projected to see about 29,000 lives lost due to El Niño’s heat.
In Brazil, heat-related deaths are projected to be higher than average each month, totaling about 19,000 deaths over the forecast period.

A Note on the Data: The projected total heat deaths from El Niño reported by the Tracker are significantly higher than what the Lab projected in a September 2026 report. Most of this increase was driven by two factors. First, the addition of March to the forecast—capturing more of the El Niño event. Second, the Tracker now accounts for observed, rather than forecasted, data for the months of August and September. The two months turned out to be much warmer than forecasted. In fact, August was the warmest August and September the second warmest September on record.

More About the El Niño Heat Mortality Tracker

The Climate Impact Lab El Niño Heat Mortality Tracker provides an estimated number of additional heat-related deaths during the current Super El Niño event compared to the 1996-2005 baseline. Estimates are available for ~3,700 ADM1 regions (state/province) across the globe for each month beginning at the start of the event in June 2026 and running through the end of the current forecast period (i.e., 6 months from the current month). The Tracker is updated each month (approximately mid-month) and is anticipated to run through the conclusion of the current Super El Niño event.

The Tracker is designed to help funders, policymakers, and practitioners prioritize where resources are needed and where immediate action can save lives. Those actions include those proven to be effective (see the Lab’s Adaptation Inventory), such as early warning systems that inform expansion of healthcare access, and the provision of water and cooling centers.

Methodology

For these mortality estimates, we leverage research from the Climate Impact Lab (Carleton et al., 2022) that quantifies the relationship between daily temperature and all-cause mortality accounting for differences in local climate, vulnerability, and adaptive capacity. Those relationships are applied to two sources of temperature information to model the estimated change in heat-related mortality for the full time period described above. We use the ERA5 global reanalysis (Hersbacch et al., 2020) for temperature data from June to the month prior to the current month to estimate changes in mortality associated with conditions that have occurred to date. For the forward-looking, 6-month forecast of changes in mortality (starting with the current month) we use surface temperature from the ECMWF SEAS5 51-member ensemble forecast (Johnson et al., 2019). ERA5 and SEAS5 are both calibrated to be consistent with the mortality model prior to projecting mortality. The result is projected changes in temperature-related mortality compared to the 1996-2025 average. Full details on the method will be published in an upcoming peer-reviewed journal.

Carleton, T., Jina, A., Delgado, M., et al. Valuing the Global Mortality Consequences of Climate Change Accounting for Adaptation Costs and Benefits. The Quarterly Journal of Economics. 2022; 137(4), 2037–2105. https://doi.org/10.1093/qje/qjac020

Hersbach, H., Bell, B., Berrisford, P., et al. The ERA5 global reanalysis. Quarterly Journal of the Royal Meteorological Society. 2020; 146: 1999–2049. https://doi.org/10.1002/qj.3803

Johnson, S. J., Stockdale, T. N., Ferranti, L., et al. SEAS5: the new ECMWF seasonal forecast system. Geoscientific Model Development. 2019; 12, 1087–1117. https://doi.org/10.5194/gmd-12-1087-2019

Attribution of datasets

ERA5: This product contains modified Copernicus Climate Change Service information. Neither the European Commission nor ECMWF is responsible for any use that may be made of the Copernicus information or data it contains. Copernicus Climate Change Service, Climate Data Store, (2024): ERA5 post-processed daily-statistics on single levels from 1940 to present. Copernicus Climate Change Service (C3S) Climate Data Store (CDS), DOI: 10.24381/cds.4991cf48. (Accessed Oct 8, 2026)

ECMWF SEAS5: Copernicus Climate Change Service, Climate Data Store, (2018): Seasonal forecast daily and subdaily data on single levels. Copernicus Climate Change Service (C3S) Climate Data Store (CDS). DOI: 10.24381/cds.181d637e. (Accessed Oct 8, 2026)