Dangerously high heat builds in California and the south-central United States

Swaths of California are sweltering and things are only expected to get worse during the Fourth of July holiday week for parts of the United States, with nearly 90 million people under heat alerts. Forecasters say Tuesday that the torrid conditions are being caused by a ridge of high pressure just off the West Coast and a separate ridge that has spawned heat warnings and advisories from Kansas and Missouri to the Gulf Coast states. California’s capital, Sacramento, is under an excessive heat warning expected to last until Sunday night, with temperatures forecasted to reach between 105 degrees and 115 degrees.