Heat dome brings dangerous temperatures to U.S. East Coast

Millions of people across the U.S. East Coast are enduring dangerous heat and humidity, with temperatures expected to reach and stay at 38C (100F) for several days. The National Weather Service has warned that the heat index could reach as high as 115F in cities such as Washington DC, Philadelphia and New York over the 4 July weekend.

Conditions and forecasts The stifling heat that has been blasting the Midwest will intensify into the Northeast and mid-Atlantic states on Thursday and Friday. Extreme heat warnings continued on Thursday from the Midwest to the Northeast. "This level of rare and long-duration heat, with little or no overnight relief, affects anyone without effective cooling and/or adequate hydration," the National Weather Service said in a warning.

By 9:00 EST (14:00 GMT) on Thursday, temperatures were already close to 90F in Washington and New York City. Maximum temperatures could hit 100F in New York Central Park on Thursday and Friday.

" Further south in the nation's capital, the city could record four days in a row of 100F heat. This has only happened twice before. On Thursday, the United States Capitol Police announced that only essential personnel would be allowed to attend a rehearsal for a 4 July concert in Washington, due to concerns about members of the public gathering amid the excessive heat.

Broader context America's northern neighbour, Canada, has also been seeing extreme heat this week, with temperatures up to 99F on the horizon in Ontario. Heat warnings are also in place across much of Quebec, including Montreal and Quebec City. Forecasters say high humidity levels will make conditions feel even more oppressive, with heat index values set to reach 115F in the coming days.