O=C=ORecord-shattering March temperatures in Western North America virtually impossible without climate change
The #heatwave poses a significant public health threat, particularly given its timing early in the season. The persistent #HeatDome is creating stable atmospheric conditions, suppressing cloud formation and precipitation, while allowing temperatures to climb, thus expected to cause persistent #heat. #ExtremeHeat is the leading cause of weather-related fatalities in the US. Limited overnight cooling and the lack of air-conditioning is expected to add to the heat stress, particularly for vulnerable populations in these parts who are not acclimatised to the heat, including tourists from cooler countries (CNN, 17 March 2026). This heat dome is breaking records for this time of the year, and is in some ways comparable to the persistent system that caused the 2021 Pacific Northwest (PNW) Heatwave. The PNW event occurred later in the year, in June, with temperatures of up to 48.9℃ (120℉) causing hundreds of fatalities (BBC, 17 March 2026).
