NASA satellite maps released Oct. 23 show the Pacific Ocean's El Niño "bulge" in October 2026 closely matching October 1997, one of the two strongest events in the satellite record. Josh Willis, a sea level scientist at NASA's Jet Propulsion Laboratory, said this year's event is "on track to be even bigger," according to NASA Earth Observatory.

The resemblance matters because the shape of an El Niño, not just its strength, influences where rain falls. In 1997, warm, high water piled up against South America, and the following winter brought heavy rain to California and across the southern United States. In 2015, another very strong event, less of that water reached the South American coast, and rainfall concentrated more over Central America and the southeastern U.S.

For residents of Los Angeles, San Diego, the San Francisco Bay Area, Houston, Atlanta and Florida's major metros, the new comparison adds weight to official outlooks that already favor a wetter winter. It does not guarantee floods in any specific community.

Satellites Flying the Same Track for 35 Years

Ocean water expands as it warms, so satellites that measure sea surface height can track where El Niño heat builds. NASA compared maps from Oct. 13, 1997, using TOPEX/Poseidon; Oct. 12, 2015, using Jason-2; and Oct. 12, 2026, using Sentinel-6 Michael Freilich. Seasonal cycles and long-term sea level rise were removed so the maps isolate short-term changes.

Willis said the value comes from a 35-year record of nearly identical satellites flying almost the same ground track, with each mission overlapping the next. That consistency lets scientists compare this year against past events with unusual confidence.

According to NASA, this year's El Niño developed much more suddenly than the 1997-98 event. By October, though, both showed the same tilt, with low sea levels in the western Pacific, high levels in the east, and warm water reaching South America.

Benchmarks From 1997 and 2015

Both earlier events upended weather worldwide. NASA notes impacts ranging from fires in Indonesia and the Amazon to drought and crop failures in southern Africa and heavy rain and coastal flooding in Southern California.

The current event is already exceptional. Nature World News previously reported that Japan's weather agency called it the strongest El Niño it has measured. NOAA's Climate Prediction Center kept an El Niño Advisory in place on Oct. 8, reporting a monthly Niño-3.4 anomaly of +2.1°C (+3.8°F) and anomalies above +4.0°C (+7.2°F) in parts of the eastern Pacific.

CPC put the chance of a historic event, exceeding all El Niños since 1950, at 54% for September through November, 83% for October through December, and 70% for November through January. It also gave a greater than 83% chance of a strong-to-very-strong El Niño through January to March 2027. These are probabilities, not a schedule.

Winter Odds for California, Texas and the Southeast

NOAA's U.S. Winter Outlook, issued Oct. 15 for December 2026 through February 2027, favors wetter-than-average conditions across the southern tier from California to Florida and along the Eastern Seaboard. It favors warmer-than-average temperatures across the northern U.S. and drought improvement in much of the East, Southern Great Plains and Southwest.

National Weather Service Director Ken Graham said a very strong El Niño "tilts the odds toward stormier weather across the South." The outlook does not forecast seasonal snowfall, and it does not predict individual storms.

The temperature side matters too. NOAA gives the greatest chances for a warmer-than-average winter in the Pacific Northwest, northern Rockies, Midwest, Mississippi Valley, much of the East and Alaska. For residents of Seattle, Denver, Chicago, and Detroit, that tilts the odds toward a milder season, though cold snaps remain possible in any winter.

The practical concern is concentrated — Southern California neighborhoods below recent burn scars face debris-flow risk in heavy rain. Low-lying coastal areas face higher tides combined with storm surge. Drivers across Texas, the Gulf Coast and the Southeast may see more frequent flooded roadways.

Households can prepare without overreacting. Check whether your home lies in a flood zone and whether your homeowners policy excludes flood damage, which standard policies usually do. National Flood Insurance Program policies typically take 30 days to take effect, so waiting for a storm warning is too late. Clear gutters and storm drains, photograph your property for insurance records, and sign up for county emergency alerts. Never drive through water over a roadway.

Limits of the Comparison

Willis cautioned that El Niño's influence passes through a chaotic atmosphere, and he described the outcome as partly a matter of chance. Looking like 1997 is a best guess — not a promise of a repeat.

Scientists also cannot yet say exactly when this event will peak or how high it will go. A wetter outlook raises odds for heavy rain events but does not identify which week or which watershed will flood.

CPC's next ENSO Diagnostic Discussion is scheduled for Nov. 12, and NOAA updates its seasonal outlooks monthly. Nature World News will track whether the 1997-like pattern holds.

The bottom line: the Pacific now looks strikingly like it did before the 1997-98 winter that soaked California, and federal forecasters favor a wet winter across the South. The most useful step now is to check flood coverage and local alerts, while remembering that seasonal outlooks shift the odds rather than set a forecast.

What Readers Want to Know

What did NASA release? Side-by-side sea surface height maps from October 1997, 2015, and 2026 showing that this year's pattern closely resembles 1997.

Why is 1997 the benchmark? The 1997-98 event was one of the strongest in the satellite record and brought heavy rain and coastal flooding to California and much of the southern U.S.

Does this mean California will flood? No. It raises the odds of a wet winter, but no agency can predict specific floods months.

Which regions does NOAA favor for a wet winter? The southern tier from California to Florida and along the Eastern Seaboard, from December through February.

How did 2015 differ? Less warm water reached South America, and rainfall concentrated more over Central America and the southeastern U.S.

What should homeowners do now? Review flood insurance, which usually takes 30 days to start, clear drains and gutters, and sign up for local emergency alerts.

When is the next official update? NOAA's Climate Prediction Center plans its next ENSO discussion on Nov. 12, 2026.