Record El Niño fuels flooding from Miami to the US Southwest

An exceptionally strong El Niño is helping to drive record-breaking flooding across the United States, from the streets of Miami to rivers in the desert Southwest.

Meteorologists at Yale Climate Connections describe the current El Niño as a "blockbuster" event that is "record-strong for late October". The UN General Assembly's president has warned it could be among the strongest since at least 1950.

Miami floods without a storm

Miami experienced six consecutive days of moderate coastal flooding from October 21 to 26, "the longest such streak on record" at the Virginia Key tide gauge, which was installed in 1994.

On one morning, the city crossed the "major" flooding threshold without any hurricane storm surge, a first on record. The flooding was driven by seasonal king tides, wind and higher sea levels rather than a storm. Seven of the 13 highest water-level days at the gauge have occurred during this year's king tides.

Records broken in the Southwest

El Niño tends to steer tropical moisture into the south-western United States, and that is what has happened this autumn.

• In Farmington, New Mexico, the San Juan River reached 14.07 feet on October 23 before the gauge stopped reporting, and a US Geological Survey gauge hit 15 feet. The previous record was 12.3 feet, set in 1909.
• The town of Hurricane, Utah, declared a state of emergency after floodwater seeped into 80 homes and 50 recreational vehicles.
• Texas Governor Greg Abbott issued a disaster declaration for El Paso County after flooding.

A global pattern

El Niño's effects are being felt elsewhere too. In Argentina's Chaco province, more than 2,200 people were evacuated as rivers rose, in flooding associated with El Niño, according to the Pan American Health Organization. In the Pacific, Typhoon In-fa passed over the far Northern Mariana Islands as a Category 4 storm on October 30.

What El Niño is

El Niño is a natural climate pattern in which surface waters in the central and eastern tropical Pacific become unusually warm, shifting rainfall and temperatures around the world and temporarily boosting global temperatures. On top of long-term warming from greenhouse gases, a strong El Niño raises the odds of record heat and extreme rainfall.

Rising sea levels, driven by climate change, mean that tides that once caused little trouble in places like Miami now regularly flood streets.

What to expect

Strong El Niño events usually peak in the Northern Hemisphere winter. In the US, that typically means a wetter winter across the southern states and milder conditions in the north. The weather extremes will be fresh in delegates' minds when the UN's COP31 climate summit opens in Antalya, Turkey, on November 9.