A single pattern in the tropical Pacific now sits behind several of the biggest weather stories in the United States: a record-quiet Atlantic hurricane season, a hyperactive eastern Pacific, rising sea levels along California's coast, and a winter outlook that leans wet across the South. In its latest monthly discussion, NOAA's Climate Prediction Center said El Niño is strengthening, with a greater than 90 percent chance of a very strong event through the Northern Hemisphere fall and winter.

The effects may carry into 2027. A Washington Post analysis that drew on data from NOAA and Europe's Copernicus Climate Change Service puts the chance that 2027 becomes the warmest year on record at 95 percent. That figure is the Post's estimate, not an official NOAA forecast. It is consistent with a well-documented pattern in which the year after a strong El Niño peak tends to set global temperature records.

For households, the connections are concrete. The same ocean warmth raises the odds of a wet winter from Southern California to the Southeast and adds inches to West Coast tides. It is also helping to suppress Atlantic hurricanes. None of these outcomes is guaranteed, because seasonal outlooks describe shifted odds, not scheduled weather.

The Pacific Engine Behind a Split Hurricane Season

In its Sept. 10 discussion, the CPC reported that the Niño-3.4 index, the main measure of El Niño strength, reached plus 1.8 degrees Celsius in August. Sea surface temperature anomalies exceeded plus 3.0 degrees Celsius in the eastern equatorial Pacific, and subsurface anomalies topped plus 10 degrees Celsius at depth. The CPC gave a 75 percent chance that the October to December season will exceed the strength of every El Niño since 1950, based on its relative index. The next monthly discussion is scheduled for Oct. 8.

On Sept. 14, CNN reported that El Niño reached super status after the weekly relative index hit plus 2.0 degrees Celsius, the threshold for the very strong category. CNN said the event was stronger than any El Niño on record for that date.

El Niño shifts where air rises and sinks across the tropics. Over the Atlantic, it tends to strengthen the upper-level winds that shear hurricanes apart, a major reason the basin has produced six tropical storms and no hurricanes this year. Over the warm eastern and central Pacific, shear eases. CNN counted 16 named storms in those regions as of Sept. 14, including two Category 5 hurricanes, and Hurricane Polo reached Category 5 off southwestern Mexico early Tuesday, Sept. 22.

That contrast is a seasonal tilt in the odds. El Niño did not create any single storm, and it does not rule out an Atlantic hurricane later this fall.

A Coastal Wave and a Wetter Southern Winter

One of the first direct effects on the U.S. mainland is moving up the West Coast. During El Niño, bursts of westerly wind send oceanic Kelvin waves east along the equator. According to NOAA Fisheries, the waves turn north after reaching Central and South America and raise coastal sea levels. Waves from this spring and summer first reached California in May and June, but NOAA research scientist Nate Mantua said their effects would likely be minor compared with what arrives this fall and winter.

North Carolina State University oceanographer Dillon Amaya told CNN that California sea levels could rise 10 to 14 inches above normal, including the latest wave, by mid-October. He called these waves "some of the first indications that El Niño is really occurring." Higher baseline water lets king tides and winter storm surf reach farther up beaches, coastal roads and bluffs in places such as Malibu, Orange County and San Diego County.

NOAA Fisheries also cautions that the unusually warm water off Central and Southern California comes from a marine heat wave that predates El Niño, so not every warm-water signal can be credited to this event.

The CPC's seasonal outlook issued Sept. 17 carries a classic El Niño signature. It favors above-normal precipitation across much of the southern United States, from California and the Southwest through Texas to the Southeast, with the strongest wet signal over parts of the Southeast. It leans drier for parts of the northern Rockies and Great Lakes and warmer than normal across much of the northern tier.

For Los Angeles, Phoenix, Houston, New Orleans, Jacksonville and Miami, that raises the chance of repeated heavy-rain events without guaranteeing them. In the Southwest, more winter precipitation is possible, but warmer air can mean rain instead of snow at some elevations, a detail that matters for spring runoff and water supplies.

Record Warmth Ahead and the Limits of the Forecast

Global temperatures typically respond to El Niño about three months after the Pacific peaks, according to an analysis by Carbon Brief. That lag is why the years following strong events, including 1998, 2016 and 2024, set records. On Sept. 3, the World Meteorological Organization said forecasts from its global producing centres show a nearly 100 percent likelihood that El Niño persists through February 2027.

"This exceptional El Niño demands exceptional preparation and response," WMO Secretary-General Celeste Saulo said in the WMO's September El Niño update. The agency also stressed that El Niño is a natural climate phenomenon and is not caused by climate change. Its heat adds temporarily to the long-term warming trend driven by greenhouse gases, which is why records become more likely.

The evidence has limits. Seasonal outlooks are probabilistic, and the WMO notes that a very strong El Niño does not bring the same impacts to every location. NOAA's strength comparisons rely on a record that begins in 1950, so claims that this is the strongest event in centuries go beyond what those products state. The 95 percent figure for 2027 is a model-based estimate that could shift as new data arrive.

Households can take practical steps now. Homeowners across the southern tier can clear gutters and storm drains and confirm flood coverage before winter, because standard homeowners policies generally exclude flooding. Coastal Californians should watch for NWS coastal flood and high-surf advisories as higher water arrives. Farmers and water managers should follow CPC and state drought updates rather than assuming a wet winter will erase deficits.

The CPC's next ENSO diagnostic discussion is scheduled for Thursday, Oct. 8, and its next seasonal outlook for Thursday, Oct. 15. El Niño is already very strong and still building. The central uncertainty is how closely this winter follows the classic pattern, and October's updates will offer the next read.

What Readers Want to Know

What is the current status of El Niño?

The CPC has an El Niño Advisory in effect and gives a greater than 90 percent chance of a very strong event this fall and winter. It also gives a 75 percent chance that October through December will exceed any El Niño since 1950.

Will 2027 be the warmest year on record?

A Washington Post analysis puts the chance at 95 percent, but that is not an official NOAA forecast. A record is considered likely because global temperatures usually peak in the year after a strong El Niño.

Did El Niño cause Hurricane Polo or the quiet Atlantic season?

El Niño tilts the odds toward a busier eastern Pacific and a quieter Atlantic. It does not cause any individual storm.

What does El Niño mean for my winter?

The CPC's Sept. 17 outlook favors a wetter winter across much of the southern U.S. and a warmer northern tier, with drier odds for parts of the northern Rockies and Great Lakes. These are probabilities, not forecasts for specific storms.

What is the Kelvin wave heading toward California?

It is a slow, large-scale ocean wave linked to El Niño that travels along the coast and temporarily raises sea level. Oceanographer Dillon Amaya expects total California sea levels to run 10 to 14 inches above normal by mid-October, which can worsen tidal flooding and erosion.

Is El Niño caused by climate change?

No. The WMO says El Niño is a natural climate phenomenon. Its heat adds to the long-term warming trend, which raises the odds of record temperatures.

When is the next El Niño update?

The CPC's next ENSO diagnostic discussion is scheduled for Oct. 8, and its next seasonal outlook for Oct. 15.