Water temperatures are shifting, but it may be more than routine. The trade winds over the Pacific have weakened, and a massive downwelling "Kelvin wave" is moving across the Pacific. This could trigger a strong El Niño this summer. According to the National Oceanic and Atmospheric Administration (NOAA), there is a 62% chance of El Niño conditions forming by late summer. There is a one-in-three chance this event reaches "strong" status, with ocean temperatures warming 1.5° Celsius above average.