"The fact that the latest robust Copernicus data reveals the January just gone was the hottest on record, despite an emerging La Niña, which typically has a cooling effect, is both astonishing and, frankly terrifying," said Bill McGuire, Emeritus Professor of Geophysical and Climate Hazards at University College London.

La Niña and record cold temperatures in the U.S. should have made Earth cooler, but January 2025 was still the hottest on record, with an average global warming of 3.15 F (1.75 C) above pre-industrial levels.