A record-breaking heat dome has turned Independence Day into a public-health emergency across the eastern United States, with federal scientists reporting extremely high rates of heat-related illness as millions of people stream outdoors for the Fourth of July.
Washington DC was forecast to hit 102F (39C) on Saturday, which would make it the hottest 4 July on record in the capital. Philadelphia and New York City were expected to approach 100F (38C), with heat index values near 105F (41C) as thick humidity pushed the 'feels like' temperature higher still.
