Extraordinary heat in US Northeast arrives to clash with revelry

Multiday warnings of extreme heat landed in New York, Boston and Philadelphia on Wednesday as sultry weather pushed east just ahead of Fourth of July celebrations in a region that revels in its role as a historic hub of US independence.

Temperatures in the high 30s Celsius were forecast for the Northeast; Philadelphia and Boston could top 38 C by Thursday.

Throw in humidity, and the real-feel heat index will be even higher at times, the National Weather Service said.

A heat dome — high-pressure ...