A record-breaking "scorcher" heatwave is underway in Southern California on March 17 and dangerous heat reaching up to triple digits will spread across much of the Southwest, forecasters said.
The heat is expected to stretch into the weekend and is likely to challenge or shatter several daily records, and potentially records for the entire month of March, according to the National Weather Service.
More than 18 million people were under extreme heat warnings the morning of March 17 across Southern California, southern Nevada and parts of Arizona. Millions more were under heat advisories in the region. The weather service office in Los Angeles warned of "dangerously hot" temperatures.
"There is a HIGH risk for heat illness this week, with conditions remaining warm overnight adding to the heat risk," the weather service said.
What makes this heatwave so unusual and dangerous, forecasters say, is not just the level of heat, but also the timing. Some major cities will see temperatures in the high 90s and triple digits weeks or months before they normally would.
