Heavy Precipitation causing the August 2025 Lagos floods Strengthened by Human-Driven Climate Change

Contact Authors

• Theophilus Tabuke (Doland Resources and Services Limited, Nigeria) - theophilustabuke@gmail.com - EN

• Davide Faranda (IPSL-CNRS, France) - davide.faranda@lsce.ipsl.fr - EN/FR/IT

Citation

• Tabuke, T.& Faranda, D. (2026). Heavy Precipitation causing the August 2025 Lagos floods Strengthened by Human-Driven Climate Change. ClimaMeter, Institut Pierre Simon Laplace, CNRS. https://doi.org/10.5281/zenodo.21409190

Press Summary

• Heavy rainfall events similar to the August 2025 Lagos floods are up to +6 mm/day heavier and up to +0.4 °C warmer in the present climate than they would have been 30 years in the past, particularly prior to 1987. This is obtained not only across the Lagos coastal zone but across the broader Gulf of Guinea region.

• The August 2025 Lagos floods were driven by very exceptional meteorological conditions.

• We ascribe the heavy precipitation associated with the August 2025 floods to human-driven climate change, and natural climate variability likely played a modest/minor role.

Event Description

On the 3rd of August 2025, Lagos, one of Nigeria’s commercial cities, experienced extreme and sustained heavy rainfall. The rainfall intensity reached over 40–45 mm/day across the metropolitan area. Different news sources pointed out that the downpour began on the night of the 3rd of August and continued through the 4th of August. This incessant rainfall clogged and overwhelmed the drainage infrastructure within the metropolis and triggered catastrophic flooding across Ikorodu, Lekki, Ajegunle, Agege, Surulere, Gbagada, Victoria Island and Yaba, among other communities. Homes as well as vehicles were submerged across the city. Major arterials connecting different parts of the state were rendered impassable; businesses remained closed and thousands of residents were either displaced or stranded. The Lagos State Government, in response to this climatic disruption, issued emergency evacuation orders for low-lying communities in Ikorodu, Ajegunle and Lekki. The National Emergency Management Agency (NEMA) reported that the August 2025 flooding claimed the lives of 191 individuals while leaving 94 people missing and 239 injured.

During the August 2025 Lagos floods, the surface pressure anomaly pattern displayed a persistent negative anomaly of up to −1 hPa over the Lagos coastline. This reveals a well-developed low-pressure system that channelled intense onshore monsoon flow into the region. The wind speed data show strong winds in excess of 25–30 km/h bringing warm, moisture-laden air from the Gulf of Guinea inland over the Lagos metropolitan area. The temperature anomaly pattern shows positive anomalies of up to +0.5 °C over the Lagos metropolitan area. The precipitation data confirm rainfall totalling 40–45 mm/day over both central and coastal Lagos, with locally higher accumulation around Ikorodu and the northern metropolitan area. The synthesis of anomalous surface pressure, elevated temperatures and intense onshore winds not only created conditions for an extreme peak-monsoon rainfall event but also exacerbated its occurrence. This analysis relies on ERA5 reanalysis data and does not incorporate local rain-gauge observations from Lagos, which would allow direct validation of precipitation totals. The ClimaMeter methodology is based on atmospheric-circulation analogues and does not use numerical model simulations. The framework cannot account for the impact of local land-use change, urban expansion, or drainage infrastructure on flood outcomes.

Climate and Data Background for the Analysis

According to Chapter 11 of the Intergovernmental Panel on Climate Change (IPCC) Assessment Report 6 Working Group 1 (IPCC AR6 WG1), it is assessed with high confidence that heavy precipitation events have not only increased in frequency but also in intensity across most parts of Africa, and this trend is projected to continue due to global warming. Chapter 9 of the IPCC AR6 WG2 (IPCC AR6 WG2) draws attention to the fact that, without adaptation, the aggregate damages from sea-level rise and coastal extremes to major African cities could reach USD 65–86.5 billion by 2050.

In recent West African climatic scholarship, different studies have documented an intensification of short-term, high-intensity rainfall events since the 1990s. This intensification has been associated with the gradual recovery of the Sahel region from the drought era and with the ongoing thermodynamic intensification of the monsoon under warming (Kendon et al., 2019). Lagos has been predicted to experience severe events as it sits at an average elevation of 1.5 metres above sea level. Recent flooding events in Lagos are already confirming this projection, as evidence of a measurable increase in extremely short-duration rainfall over its coastal zone emerges.

Our analysis approach rests on looking for weather situations similar to those of the event of interest having been observed in the past. For the August 2025 Lagos floods, we have low confidence in the robustness of our approach given the available climate data, as the event is very exceptional in the data record.

ClimaMeter Analysis

We analyse here (see Methodology in Faranda et al., 2024 for more details) how events similar to the August 2025 Lagos floods have changed in the present (1987–2024) compared to what they would have looked like if they had occurred in the past, in the region [0°E–9°E, 0°N–9°N].

Surface pressure changes show that the mean sea-level pressure anomaly associated with these circulation patterns has remained broadly stable between the two climate periods, with changes of less than ±0.1 hPa over the Lagos region. This indicates that the large-scale atmospheric configuration driving heavy rainfall events of this type has not changed between the historical and present climate periods.

Temperature changes show that events similar to the August 2025 Lagos floods produce temperatures that in the present climate are up to +0.4 °C warmer over the Lagos urban area and coastline than they would have been in the past. This increase in warmth translates into an increase in atmospheric capacity to hold moisture of about 4%, directly amplifying rainfall intensity in events driven by similar circulation patterns.

Precipitation changes show that circulation patterns associated with these totals are, in the present climate, up to +6 mm/day heavier over parts of the Lagos coastal zone than they would have been in the past. Some areas to the north of Lagos show a slight drying tendency of up to −4 mm/day, reflecting the spatial complexity that characterises West African monsoon dynamics under warming. There was also a modest increase in wind speed over Lagos and Lomé, while precipitation changes over the West African coastal cities are all within the range of uncertainty.

Similar past events have remained concentrated in the July–September monsoon season in both historical and current climate periods, although a slight relative increase in the fraction occurs in September in the current period compared with the historical baseline. This elongates the window for high-risk rainfall into the later part of the monsoon season.

Finally, we cannot detect any influence of natural climate variability on the event. The El Niño Southern Oscillation (ENSO, H=0, p=0.060), the Atlantic Multidecadal Oscillation (AMO, H=0, p=0.249) and the Pacific Decadal Oscillation (PDO, H=0, p=0.156) show no statistically significant association with this event type. This means that the changes we see in the event compared to the past are mainly due to human-driven climate change.

Conclusion

Based on the above, we conclude that heavy rainfall events similar to the August 2025 Lagos floods have become up to +6 mm/day heavier and up to +0.4 °C warmer in the present climate than in the past across the Lagos coastal zone. We interpret the August 2025 Lagos floods as:

• An event driven by very exceptional meteorological conditions.

• Whose characteristics can be ascribed to human-driven climate change.

These findings reiterate the urgency of accelerating climate-adaptation investment in Lagos. Attribution science, which focuses on demonstrating the measurable fingerprint of climate change on specific events, provides the scientific basis for climate litigation and adaptation-finance mobilisation. The recently published Lagos Climate Adaptation and Resilience Plan (LCARP) is a step in the right direction, as it provides a policy framework coupled with pragmatic implementation for addressing a rapidly warming climate. This is the first ClimaMeter attribution analysis of an extreme weather event in Lagos and among the first rapid attribution analyses of any extreme weather event in West Africa.

References

• Faranda, D., Messori, G., Coppola, E., et al. (2024). ClimaMeter: contextualizing extreme weather in a changing climate. Weather Clim. Dynam., 5, 959–983. https://doi.org/10.5194/wcd-5-959-2024

• Faranda, D., Bourdin, S., Ginesta, M., et al. (2022). A climate-change attribution retrospective of some impactful weather extremes of 2021. Weather Clim. Dynam., 3, 1311–1340. https://doi.org/10.5194/wcd-3-1311-2022

• IPCC (2021). Climate Change 2021: The Physical Science Basis. WG1 AR6, Chapter 11: Weather and Climate Extremes. Cambridge University Press. https://www.ipcc.ch/report/ar6/wg1/

• IPCC (2022). Climate Change 2022: Impacts, Adaptation and Vulnerability. WG2 AR6, Chapter 9: Africa. Cambridge University Press. https://www.ipcc.ch/report/ar6/wg2/

• Kendon, E. J., et al. (2019). Enhanced future changes in wet and dry extremes over Africa at convection-permitting scale. Nature Communications, 10, 1794. https://doi.org/10.1038/s41467-019-09776-9

• Lagos State Government (2023). Lagos Climate Adaptation and Resilience Plan (LCARP). Ministry of Environment and Water Resources.

• National Emergency Management Agency (NEMA) (2025). 2025 Flood Season Situation Report. Abuja: NEMA.

• Nigerian Hydrological Services Agency (NIHSA) (2025). 2025 Annual Flood Outlook. Abuja: NIHSA.

• Nigerian Meteorological Agency (NiMet) (2025). 2025 Seasonal Rainfall Prediction. Abuja: NiMet.

• Daily Trust (2025, August 5). Residents, motorists stranded as flood hits Lagos. https://dailytrust.com

• Punch (2025, August 8). Flooding: Lagos community counts losses, blames abandoned drainage construction. https://punchng.com

• TVC News (2025, August 6). Lagos warns Lekki, Ikorodu, other residents to relocate over flood risk. https://tvcnews.tv

• Vanguard (2025, August 4). Lagos submerged as floods sack homes, paralyse traffic, halt businesses. https://vanguardngr.com