Hurricane Patricia was the most intense tropical cyclone on record in the eastern North Pacific or Atlantic, reaching a peak intensity of 95 m s−1 only 30 h after attaining hurricane status (33 m s−1). Here it is shown that exceptionally warm sea surface temperatures (SSTs), a deeper than normal thermocline, and strong near-surface salinity stratification all aided Patricia's rapid intensification, combining to increase its Potential Intensity by 1–14 m s−1. Anomalous surface warming and thermocline deepening along Patricia's track were driven by prolonged El Niño conditions during 2014–2015 and punctuated by the buildup to the extreme El Niño of 2015–2016. In the region where Patricia intensified, SST was 1.5° C higher and sea surface height was 10 cm higher compared to conditions during the last extreme El Niño in 1997, emphasizing the extraordinary nature of the 2015 anomalies.