Nature Communications, 19 March 2026<\/p>\n
A reduction in western Eurasian snow cover played a pivotal role in the record-breaking January 2025 wildfires in Southern California. These proved the costliest in recorded history, claiming at least 31 lives and destroying more than 16,000 buildings, obliterating nearly all structures across nearly 80 square miles. Its unusual timing suggested larger climatic forces at play, and observations together with climate models now confirm that low snow cover in Eurasia played a strong role. Such low Eurasian snow cover triggers Rossby wave trains \u2013 large, meandering air patterns that travel across the Pacific \u2013 which can generate dangerous wildfire conditions in California. It also can lead to North American winter temperature dipole conditions, with warming in the west and cooling in the east. The study demonstrates that Eurasian snow cover can have predictable impacts on climate extremes elsewhere, including wildfire risk, and highlights the importance of integrating cryosphere monitoring into early-warning and climate adaptation strategies.<\/p>\n