Unprecedented Heat Dome Forms Early (Image Credits: Unsplash)
Los Angeles, San Francisco, and Phoenix — A massive heat dome is building over the Southwest, promising temperatures more typical of midsummer than mid-March. Meteorologists described the incoming event as unprecedented, with prolonged highs poised to topple daily and monthly records across California and Arizona.[1][2] Officials issued rare early-season heat advisories and watches, urging millions to prepare for a multiday marathon of extreme warmth that could exacerbate drought conditions and strain public health resources.
Unprecedented Heat Dome Forms Early
The powerful ridge responsible for this heat emerged from an unusually strong mid-tropospheric high-pressure system, the strongest observed in the Southwest during March. Subsidence within the ridge triggered adiabatic warming, drying the air and amplifying temperatures across a vast area from the California coast to Arizona deserts.[2] This setup arrived in two phases: an initial surge starting Thursday, peaking Friday in Southern California, followed by an even broader intensification next week.
Forecasters noted the event’s exceptional duration and scope, with heat persisting through late March. Unlike typical spring warm spells, this dome trapped warmth under clear skies, preventing any cooling relief. The National Weather Service highlighted its potential to become record-shattering in intensity.[2]
City-by-City Temperature Outlook
Los Angeles faced forecasts approaching 100°F in the basin areas Thursday and Friday, with valleys like the San Fernando potentially hotter. Inland spots such as Palm Springs eyed 110°F, while coastal influences moderated some readings to the mid-90s. San Francisco, often shielded by fog, still braced for Bay Area highs near 90°F, especially inland.[2][3]…