4 questions about El Niño’s role in Hurricane Isaias

This is a broad seasonal influence, not a switch that turns hurricanes off. Colorado State University hurricane expert Phil Klotzbach described El Niño as one of several factors involved in Isaias’s formation. He also told PBS News that El Niño “still is certainly driving the bus” for the season.

NOAA’s 2026 Atlantic outlook said El Niño was interfering with conditions associated with higher hurricane activity. Its Oct. 8 assessment said the pattern was strengthening and gave greater than an 83% chance that strong-to-very-strong conditions would persist through January-March 2027.

NOAA also estimated the chances that El Niño would reach its historic-strength threshold at 54% for September-November, 83% for October-December and 70% for November-January. Those are probabilities for overlapping three-month periods, not guarantees of a particular storm or its effects. NOAA said El Niño-consistent impacts were more likely, but not assured, even if the event reached historic strength.

Why could Isaias develop in the Gulf?

The wind conditions were not the same across the Atlantic region. While El Niño-related wind shear can make formation more difficult in the Caribbean, forecasters described shear in the Gulf as weaker than in other tropical regions.

Lindsey Long, a meteorologist with NOAA’s Climate Prediction Center, said that difference left the Gulf “a little more primed for development,” as PBS News reported. The point is not that El Niño had no influence, but that its general effect did not make every part of the basin equally unfavorable for storm development.

Klotzbach identified very warm Gulf water as another contributor to Isaias’s strengthening. The Madden-Julian Oscillation, a natural, recurring weather pattern, was also relevant to the conditions around the storm.

Together, those factors describe a mix of influences operating at different scales: El Niño’s broad effect on Atlantic activity, wind shear in the Gulf, warm water and the oscillation. The climate pattern offers important context, but it is not the whole explanation for how Isaias developed and strengthened.

How does Isaias fit in an El Niño season?

Isaias was the Atlantic season’s ninth named storm, and none of the eight before it had reached hurricane strength, AP reported. The agency described a normal season as producing 14 named storms, seven hurricanes and three major hurricanes. Those figures provide a season-wide yardstick, not a forecast of whether one storm will form in a particular place.

The National Hurricane Center said Isaias strengthened to hurricane status on Wednesday, Oct. 7. Its 1500 UTC advisory on Thursday listed maximum sustained winds of 75 knots. The storm’s development is consistent with the distinction forecasters draw between a pattern that tends to reduce activity overall and local conditions that can still support a hurricane.

The historical record also shows that El Niño does not rule out Atlantic hurricanes. AP cited Lili in 2002, Ivan in 2004 and Idalia in 2023 as hurricanes that affected the eastern United States during earlier El Niño periods.

A season can therefore have conditions that generally hinder Atlantic storm formation and still produce a dangerous hurricane. The seasonal pattern describes a tendency across a broad area and stretch of time; it does not determine whether an individual storm will develop or what it will bring to a community.

What hazards did forecasters warn about along the Gulf Coast?

The National Hurricane Center’s Oct. 8 forecast discussion warned of life-threatening storm surge along parts of the Florida Panhandle, southern Alabama and southern Mississippi. Forecasts for communities along and inland from the northern Gulf Coast also included damaging winds and flooding. These were anticipated hazards, not confirmed impacts.

AP’s Oct. 8 report placed a possible landfall late Friday, Oct. 9, or early Saturday, Oct. 10. That was the forecast at the time, not a report of a landfall that had occurred. The immediate concerns for residents came from the storm’s projected hazards and path, not from whether El Niño was the main influence on its formation.

Long cautioned against treating a season-wide pattern as reassurance. “It only takes one storm for a lot of possible destruction. So you don’t want to put your guard down,” she told PBS News.

That is the practical distinction: El Niño helps explain the background conditions shaping Atlantic activity, while local forecasts address the threats facing people near Isaias. A tendency toward fewer storms across a season does not make the risks from one approaching hurricane smaller.