Warm “hairdryer” gusts that rush down mountainsides are implicated in catastrophic heatwaves and wildfires – and they might escalate further due to climate change. It’s a term that, in German, translates to “hairdryer” as well. That encapsulates the essence of it. A scorching, arid breeze that cascades down a mountainside, searing everything in its trajectory. This intense phenomenon is known as the Föhn. These winds – also referred to as Santa Ana winds in California – frequently appear during heatwaves, elevating temperatures to unbearable extremes in certain, literal hot spots. Under the right circumstances, they can also ignite flames into ferocious wildfires. In January 2025, a formidable Santa Ana windstorm with gusts anticipated to peak at 100mph (160km/h) swept across southern California. The winds, which the National Weather Service labeled as “life-threatening,” propelled flames originating from the mountains west of Los Angeles into a swiftly spreading wildfire that consumed the already parched vegetation and devastated the Pacific Palisades neighborhood near Santa Monica, necessitating the evacuation of at least 30,000 residents. In August 2023 in Taiwan, Föhn winds were linked to a sweltering 39C (102F) heat in the country’s southeast. The same type of wind may have intensified the extreme heatwave in France, and some suggest that it contributed to the tinder-dry conditions that fueled the catastrophic wildfires in Maui, Hawaii, claiming at least 106 lives. The Föhn effect can manifest in significantly colder regions as well, including Antarctica, where it can play a role in the swift breakdown of ice shelves. Furthermore, in 2018, it was held responsible for pushing a considerable amount of ice away from Greenland’s coast. The unusual strength of Föhn winds could be far-reaching. There is an enduring folklore belief that they can induce adverse psychological impacts, such as depression and suicidal ideation. While concrete evidence is scarce, it’s reasonable to assert that Föhn winds deserve serious attention. Luckily, science aids us in comprehending their nature – and the dangers they represent. “Typically, a mountain or a series of hills is necessary for the Föhn effect to occur,” states Liz Bentley, chief executive of the Royal Meteorological Society. A humid breeze will ascend one side of a mountain to reach the cooler upper atmosphere, where moisture condenses to form clouds or precipitation near the summit, she clarifies: “This releases energy into the atmosphere,” resulting in increased air temperatures.