In 2023, an extreme coastal El Niño event struck the coastal regions of Peru and Ecuador, causing severe rainfall, flooding, and a record dengue outbreak. Observations and ocean model experiments revealed that northerly alongshore winds and westerly wind anomalies in the eastern equatorial Pacific, initially associated with a strong Madden-Julian Oscillation and a cyclonic disturbance off Peru, drove the coastal warming through suppressed coastal upwelling and downwelling Kelvin waves. Atmospheric model simulations indicated that the coastal warming favored the observed wind anomalies over the far eastern tropical Pacific by triggering deep convection, forming a positive feedback loop. This feedback loop further amplified the coastal warming. In May, the seasonal background cooling prevented deep convection and the coastal Bjerknes feedback, leading to the weakening of the coastal El Niño. The 2023 coastal El Niño is rare but predictable at one month lead, which can help protect lives and properties. The study used observations and comprehensive ocean and atmospheric general circulation models to investigate the evolution and mechanisms of the 2023 extreme coastal El Niño, highlighting the importance of local wind anomalies in the far eastern Pacific and the coastal Bjerknes feedback in driving and amplifying the event.In 2023, an extreme coastal El Niño event struck the coastal regions of Peru and Ecuador, causing severe rainfall, flooding, and a record dengue outbreak. Observations and ocean model experiments revealed that northerly alongshore winds and westerly wind anomalies in the eastern equatorial Pacific, initially associated with a strong Madden-Julian Oscillation and a cyclonic disturbance off Peru, drove the coastal warming through suppressed coastal upwelling and downwelling Kelvin waves. Atmospheric model simulations indicated that the coastal warming favored the observed wind anomalies over the far eastern tropical Pacific by triggering deep convection, forming a positive feedback loop. This feedback loop further amplified the coastal warming. In May, the seasonal background cooling prevented deep convection and the coastal Bjerknes feedback, leading to the weakening of the coastal El Niño. The 2023 coastal El Niño is rare but predictable at one month lead, which can help protect lives and properties. The study used observations and comprehensive ocean and atmospheric general circulation models to investigate the evolution and mechanisms of the 2023 extreme coastal El Niño, highlighting the importance of local wind anomalies in the far eastern Pacific and the coastal Bjerknes feedback in driving and amplifying the event.