Record-breaking March heat sweeps California and Southwest

An anomalously early heat wave is boiling the western U.S., with Southern California highs reaching the 90s and parts of Arizona and Nevada in the triple digits as about 39 million people are under heat alerts. The National Weather Service says a high-pressure heat dome will drive daily record highs and likely extend through the week, raising concerns about heat risks, drought, wildfire potential, and water supply. The West is also contending with reduced snowpack, while a separate winter storm hits the Midwest and Hawaii endures heavy rains from an atmospheric river.