Multi-scale climate teleconnections amplify extreme precipitation hazards in central-southern Chile

Study region: Central-southern Chile (30°S–40°S) is highly vulnerable to hydroclimatic disasters, where extreme precipitation is the primary driver of severe flooding, making the accurate assessment of localized, intense rainfall hazards critical for water security and infrastructure. Study Focus: Traditionally, hydroclimatic hazard assessment has relied on stationary paradigms, neglecting multiscale climate dynamics. We introduce a comprehensive multivariate framework using Non-Stationary Extreme Value Theory (NSEVT) to evaluate daily precipitation extremes from 1981 to 2025. Applying a Peaks Over Threshold approach across a newly reconstructed, high-resolution observational dataset, we isolate the concurrent impacts of the El Niño-Southern Oscillation (ENSO), the Antarctic Oscillation (AAO), the Madden-Julian Oscillation (MJO), and long-term background trends. New hydrological insights: Our findings reveal that teleconnections act as highly heterogeneous spatial amplifiers or mitigators of hazard. Specifically, warm ENSO phases and active sub-seasonal MJO states can triple the magnitude of 100-year extreme return levels. Conversely, the positive AAO phase generates a spatial dipole, statistically mitigating hazard in central Chile while exacerbating hazards in northern Patagonia. We demonstrate that catastrophic, localized runoff potential is significantly amplified when these atmospheric modes synchronize. These findings highlight that a multivariate extremes analysis provides a better framework for characterizing the temporal variability modes of extreme events, including a more robust assessment of long-term temporal trends.