Record-setting heavy precipitation occurrence in 2024.

Precipitation extremes have increased globally in recent decades, consistent with a warming climate. We find that 2024 experienced a record-high frequency of heavy (≥99th percentile; FP≥99) precipitation events globally based on MSWEP (Multi-Source Weighted-Ensemble Precipitation) observations from 1979 to 2025. This extends a long-term trend of ∼0.03%/decade in FP≥99, with similar but more uncertain increases for the 99.9th percentile. Unlike prior high FP≥99 years, 2024's record was more globally distributed and emerged from a distinct seasonal evolution. El Niño and rare concurrent multi-basin tropical ocean warmth drove elevated extremes early in the year, before lagged global tropospheric responses and long-term warming sustained and amplified extremes through boreal summer. Climate models indicate that years with 2024-level FP≥99 typically require either stronger El Niño forcing or concurrent multi-basin sea surface temperature (SST) anomalies. Diagnostic projections within constrained ensemble members suggest that ∼40% of the 2024 anomaly aligns with global mean temperatures and ∼20% with El Niño variability, with some of the remainder linked to basin-scale SST structure.