Countdown to Collapse: Stability Dynamics Observed Before the 2025 Iberian Power System Blackout

On April 28th, 2025, at 12:33 p.m., a largescale blackout-one of the most significant in European his-tory-affected Spain, Portugal, and parts of France, leaving tens of millions of people without electricity and resulting in economic losses estimated in hundreds of millions of euros. This paper provides an overview of the power system conditions prior to the event, supported by a timeline of key occurrences. Several of these are identified as possible early signs of stress within the system. To investigate this, the study applies a data-driven method known as Dynamic Mode Decomposition to analyze the system dynamics.