El Niño Ties a Daily Record NOAA’s Index Has Not

Daily warmth in the central Pacific hit 3.07C on 19 September, tying the 2015 El Niño on a widely used gauge. Zeke Hausfather, a Berkeley Earth climatologist, said September is very likely to post the highest monthly gap on that record unless the next week turns strange.

NOAA’s official climate-adjusted index is still below its own peak. Cattle are already dying in Honduras, and the Panama Canal is running 32 ships a day.

Two Gauges, One Pacific

Hausfather’s daily figure uses NOAA satellite-and-buoy sea-surface data for the Niño 3.4 box, an imaginary stretch of the east-central Pacific, and compares it with a rolling 30-year average. As of 19 September that daily gap stood at 3.07C, a statistical tie with 3.08C on 18 November 2015. El Niño events this strong usually keep climbing after mid-September, and this one started earlier than the last giants.

By early September in both 1997 and 2015, the same daily reading was about 1.9C, more than a degree cooler than this year. August, the last full month in the file, sat near 2.45C. That is hotter than every prior monthly peak except 2015-16 at 2.75C and a reconstructed 1877-78 event near 2.7C built from sparse ship logs.

HOW THE TWO EL NIÑO GAUGES COMPARE

A tenth of a degree in that Pacific box is not what emptied the cattle troughs in southern Honduras. The harm is running on soil moisture, lock water and peat, which do not wait for a daily tie to be certified.

NOAA Dropped the Old El Niño Yardstick in February

On 1 February NOAA switched to the Relative Oceanic Niño Index as its operational ENSO gauge. The old Oceanic Niño Index asked only whether Niño 3.4 was warmer than a 30-year average for that box. Because the whole tropical ocean has been heating, that fixed baseline made recent events look stronger than the atmosphere was actually feeling.

RONI starts with the same Niño 3.4 gap, then subtracts the average gap across the tropics from 20 degrees south to 20 degrees north. What remains is how much extra warmth sits in the ENSO region relative to the rest of the tropical belt. NOAA says that contrast tracks the Walker Circulation, and therefore drought and rain, more closely than a static baseline.

WHAT RONI MEASURES

• The contrast: It takes the Niño 3.4 sea-surface gap and subtracts the tropical-mean gap, then rescales the result to the old index’s range.
• The threshold: El Niño is a RONI of +0.5C or higher; La Niña is -0.5C or lower, for overlapping three-month seasons.
• The tradeoff: The method can shrink the apparent size of a broad, strong El Niño whose warmth spills outside the Niño 3.4 box.

The agency’s June-August 2026 RONI of 1.4C is the official three-month reading, with El Niño on the books and an El Niño Advisory in force. Hausfather’s daily RONI in mid-September was about 2.5C, a high for the date, still about 0.7C shy of the 1982-83 daily peak, which arrived in late December. The 1982-83, 1997-98 and 2015-16 events added between 0.5C and 1.9C on that gauge between mid-September and their crests.

Cattle Are Dying in the Dry Corridor

The same Pacific pattern has already dried the Central American Dry Corridor, a belt that cuts through Honduras, Guatemala, El Salvador, Nicaragua and Costa Rica. More than 10 million people live there, and United Nations figures put 80 percent of small-scale producers in poverty. Locals keep calling this the worst drought in living memory.

In San Lorenzo, in southern Honduras, about 100 cows have died in recent months. Their bones lie on cracked ground while farmers milk the animals that are left. Lidia Ochoa, 76, said, “Sometimes I break down in tears. Sometimes you eat, sometimes you don’t.” She also said, “We had never seen anything like this.”

Darwin Cruz, a small dairy farmer in the same village, sold two cows after the dry spell tightened in June and lost a third. The three that remain give about a quarter of their usual milk, the income that feeds his wife and two daughters. He said that if the rain stays away he will sell the last of them.

Elvira Pasa, an Indigenous leader in Cunen in northern Guatemala, said, “All the corn harvests are going to be lost.” Some villagers are already paying about 50 percent more for corn. Guatemala already had a child-malnutrition problem. The drought is making it worse.

WHO IS ALREADY SHORT OF FOOD

• Guatemala: The food-security secretariat SESAN puts 3.2 million people, about 17 percent of the country, in acute food insecurity for July through September.
• Honduras: UNAH figures count 1.8 million people already hit, with as many as 2.2 million possible by year-end.
• Marcovia: The Choluteca municipality declared an emergency on 5 August for more than 15,000 families short of water and crops.
• The global add-on: The World Food Programme in August said a strengthening El Niño could push 49 million more people into acute hunger by the end of next year, lifting the total from 225 million to 274 million, about 22 percent, with Central America showing an 83.1 percent jump in the countries it studied.

Latin America and the Caribbean could see more than 16 million people affected, the sharpest regional rise in that WFP scan. A tenth of a degree in Niño 3.4 will not reverse a failed primera planting. The corridor’s maize and beans were supposed to be in the ground when the heat arrived.

How Many Ships the Canal Will Let Through

From 15 September the Panama Canal Authority has been running 32 ships a day, nine of them through the big Neopanamax locks and 23 through Panamax, after rainfall in the watershed fell 34 percent. Each crossing still lifts a ship about 26 metres, 85 feet, on fresh water from Gatun Lake, so a dry lake means fewer slots and shallower drafts. The waterway carries about 5 percent of world trade.

Daily transits had already dropped from 36 to 34 earlier in September. Neopanamax draft, once 15.2 metres or 50 feet, is now capped at 14.63 metres, with a further cut to 14.48 metres deferred to 1 October. Gatun sat just over 84 feet in August, about a foot below the five-year average for the month, after inflows into the watershed fell 44 percent in the hydrological year.

THE CANAL’S WATER RATION

1. July 2026: Maximum draft in the big locks starts falling from 15.2 metres as El Niño dries the rainy season.
2. 20 August 2026: The Panama Canal Authority tells customers it will cut daily transits and delay the next draft steps to save lake water.
3. 4 September 2026: Daily slots fall to 34, with nine reserved for Neopanamax ships.
4. 15 September 2026: Daily slots fall to 32, and Panamax locks drop to 23.
5. 1 October 2026: A tighter 14.48-metre draft, postponed from early September, is scheduled to take effect.

Filipe Gouveia, shipping analysis manager at BIMCO, said bulker transits through the canal have fallen 22 percent year-on-year since the start of July, as tankers compete for the remaining slots and El Niño points to still-lower lake levels. About 15 percent of U.S. seaborne maize and soy usually takes this shortcut to East Asia and the west coast of the Americas. Ships without a booking were already waiting 8.5 days northbound and 7.7 days southbound in late August, with 36 unbooked vessels in the queue on 20 August. The SK Shipping LPG carrier G. Arete paid $4.6 million at auction to jump the line.

Indonesia’s Fires Are Tracking the 2015 Disaster

On the other side of the Pacific, the same pattern has shut off rain over Indonesia’s peat and forest. Forestry Minister Raja Juli Antoni said, “We have not yet escaped the threat of El Niño.” He called September “our month of struggle, our field of struggle.” The government has put more than 50 aircraft over the hotspots, including water bombers and cloud-seeding planes, with Japanese Chinooks in the mix.

Mark Parrington, a senior scientist at the Copernicus Climate Change Service, said Indonesia always sees some fire from August into October or November, but not on this scale except in prior El Niño years. Nisa Novita, a peat researcher at the Indonesian conservation group YKAN, said the 2026 season is running very close to 2015, when fires chewed through 2.6 million hectares.

INDONESIA’S 2026 FIRE TOLL SO FAR

• Official burn area: The Forestry Ministry counted 202,000 hectares from January through July, after 107,465 hectares in the first half of the year, 110 percent above the same stretch of 2023.
• Haze exposure: Health ministry figures show more than 12.5 million people exposed across seven provinces on Borneo and Sumatra.
• Clinic load: Wildfire-related respiratory cases in those provinces rose to 113,336 by 9 September, from 50,891 on 1 September.
• Carbon so far: The Global Fire Emissions Database logged 76 million tonnes of carbon by 7 September, on a path that resembles 2015’s full-year 333 million tonnes.

Copernicus Fire Emissions Watch put Indonesia’s release in the first week of September at 19.7 million tonnes, more than a third of the global wildfire total for those days. The 2015 haze has been linked to more than 100,000 premature deaths across the region. Pontianak on Borneo has spent days under white-yellow smoke with visibility under a kilometre, enough to delay flights and slow the crews sent to fight the next fire.

Galápagos Corals Put the Last 40 Years Outside a Millennium

Scientists still argue over whether greenhouse warming makes El Niño events themselves stronger, even as they agree a warmer atmosphere holds more moisture and a warmer land surface dries out faster. A Science paper published on 27 August, built from Galápagos coral geochemistry across a millennium, comes down on the stronger-events side for the eastern Pacific.

Julia Cole, professor and chair of Earth and environmental sciences at the University of Michigan, led a team that cored 13 living and fossil corals. They read strontium-to-calcium ratios and oxygen isotopes, millimetre by millimetre, in colonies that grow one to two centimetres a year. Modern eastern-Pacific ENSO swings came out 37 percent larger, plus or minus 8 points, than the preindustrial stretch from 1000 to 1850, and 16 percent larger, plus or minus 9 points, than the 1850-1981 stretch. The U-M newsroom said those recent events were stronger than any in the prior 1,000 years.

We don’t see a time in the past where El Niños have been as strong as today, and we show that the strength of El Niño changes in parallel with the warming of global temperature. Our findings tell us that the big El Niño events of the last 40 years are not normal in the context of the last thousand years.

Julia Cole, professor and chair, University of Michigan Department of Earth and Environmental Sciences

Climate models forced with volcanoes and solar swings over the last thousand years did not produce a jump this large. Cole said the live event is stacked on global warming and could help push global temperature as high as 1.7C or 1.8C above the preindustrial mark, above the current record. That is the forecast. The Dry Corridor is the present.

The Peak Is Still Months Away

Hausfather’s September round-up of 14 seasonal models, 674 individual runs, puts the peak monthly Niño 3.4 gap later this year near 4.1C, with 80 percent of runs between 3.4C and 4.6C. Every run tops the 2015-16 monthly record. The projected margin, about 1.3C, is larger than the gap between the strongest and the fifth-strongest El Niño of the past 150 years. His July set of 667 members had a median peak of 3.6C. No forecast system has been tested against an event of this size, because none has happened, and the models ran about 0.3C too warm in August.

On 16 September, after the last dynamical model of the month arrived, he put the chance of a record event this year at 100 percent on the Oceanic Niño Index and 98 percent on RONI.

All the September dynamical ENSO models (including SINTEX) are now in, and they give a 100% chance of a record event this year using the Oceanic Niño Index (ONI) metric: pic.twitter.com/EuBQJtbPqe

— Zeke Hausfather (@hausfath) September 16, 2026

NOAA’s own briefing still gives a greater than 90 percent chance of a very strong event in Northern Hemisphere fall and winter 2026-27. El Niño’s lift in global temperature typically lags the Pacific by several months, so Hausfather expects most of that heat in 2027 rather than 2026.

On 22 September the World Health Organization called the pattern a serious health threat: extra heat, fire haze, malnutrition, cholera, and a wider range for malaria, dengue and chikungunya. Teresa Zakaria, who leads WHO’s unit on risk reduction, humanitarian operations and climate change, said the health effects are predictable and that a window to act is still open. UN Secretary-General António Guterres said earlier in September, “El Niño is being supersized before our eyes.” WMO chief Celeste Saulo said a name that means little boy in Spanish can still deliver a massive blow to communities and economies.

The daily Pacific number may yet leave 2015 behind. NOAA’s official gauge may yet leave 1982 behind. In San Lorenzo the carcasses are already on the ground, and the canal is already turning ships away.