A potent heat dome is triggering a record-breaking March heatwave across the Southwest, with approximately 70 million individuals bracing for temperatures ranging from the 90s to above 100°F throughout the weekend. Major metropolitan areas such as Los Angeles, Las Vegas, and Phoenix are poised to shatter multiple daily and potentially all-time March temperature records. Projections indicate Phoenix nearing 106°F, while Las Vegas may reach triple-digit temperatures significantly earlier than typical. Temperatures across the region are soaring 20–30 degrees above the seasonal average, with the heatwave expected to extend into early next week.