El Niño ties all-time record strength, with peak still months away

The current El Niño has tied the strongest daily reading ever recorded, and forecasters expect it to keep building through winter.

Sea surface temperatures in the central Pacific's Niño 3.4 region reached an anomaly of 3.07C on Sept. 19, statistically tying the record of 3.08C set in November 2015, according to Carbon Brief's analysis of NOAA data. El Niño typically peaks in November or December, making this September reading unusually early. The event has been developing faster than any on record since it began in June.

The National Weather Service's Climate Prediction Center estimates a 75% chance this becomes the strongest El Niño since records began in 1950. Fourteen seasonal forecast models project a peak anomaly around 4.1C — every model run exceeds the 2015–16 record.

For the Pacific Northwest, the Climate Prediction Center forecasts above-average temperatures this fall. Oregon State Climatologist Larry O'Neill cautioned that the event's unprecedented strength makes outcomes unpredictable. A cool-phase Pacific Decadal Oscillation could offset some coastal warming, and past very strong El Niños have brought Oregon wetter winters than the pattern usually produces. "We really don't have a good sense of what's going to happen," O'Neill said.