Record-Shattering March Heat Dome Scorches U.S. Southwest
Between 17-21 March 2026, an unusually persistent high-pressure ‘heat dome’ drove temperatures 25-35 °F above normal, smashing hundreds of U.S. March records—topping out at a national March record 112 °F along the CA-AZ border and forcing first-ever mid-March extreme-heat closures, warnings and cooling-center rollouts across Arizona, Nevada and California.