Heatwave blankets many parts of the US ahead of Independence Day

Millions across the US Midwest and Great Lakes region are enduring a sweltering heatwave, expected to persist through the 4/7 Independence Day holiday.

A "heat dome" will cover the central and eastern US this week, pushing heat index values – a combination of air temperature and humidity – soaring to 37.8°C in some areas. This intense heat is expected to last through the upcoming 4/7 holiday, severely impacting World Cup host cities like Boston, Philadelphia, and Kansas City.

The US National Weather Service (NWS) warned that the situation is "dangerous", increasing the risk of heat-related illnesses, especially for those without air conditioning. "This level of heat can be fatal for those who are not adequately cooled and hydrated", NWS cautioned, noting that the heat would also put significant strain on transportation, power, and water systems. Geoff Cornish, an AccuWeather meteorologist, described the event: "This week will be very, very hot. This will be an intense heatwave, a rare type of weather event".

The highest US extreme heat warning covered the entire Midwest region on 30/6. *Graphic: NWS*

Water sprinklers cool the field as players take a water break during a match between France and Sweden at MetLife Stadium, New Jersey, on 30/6.

Chicago residents jump into a lake to escape the heat as temperatures exceeded 32°C on 29/6.

A visitor attempts to cool down with a fan and ice water while queuing for an event at the National Mall in Washington D.C. on 30/6.

Adults and children play to escape the heat at the Crown Fountain in Millennium Park, Chicago.

The Midwest is currently under the highest US extreme heat warning. Authorities in Kansas City and other parts of Missouri have issued severe heat warnings until the night of 3/7, with heat index values ranging from 40.6 to 43.3°C. Much of Michigan, along with Illinois, Ohio, Indiana, Kentucky, and most of Iowa, are under extreme heat advisories.

A man pours water into an insulated cup in Nashville, Tennessee.

Leonardo Harold, 18, lies in front of a vent to cool off during an Independence Day celebration in Washington D.C.

NWS reported that air temperatures in Detroit reached nearly 37.8°C and could remain at this level on 2/7. Detroit authorities have established multiple cooling centers for residents, some open until 23h.

Residents cool off at Silver Beach along Lake Michigan, one of the US Great Lakes, in St. Joseph, Michigan.

A man cools down after jogging at Hart Plaza in Detroit, Michigan.

The Northeast, including New York City and Boston, will be the next region to face an intense heatwave extending through the holiday. New York City could experience heat index values up to 42.8°C, with nights offering little relief. Heat index values in Boston and much of southern New England could surge to 43.9°C, placing the region under an advisory from 1/7.

Chicago has also been significantly affected. The Chicago History Museum offered free admission on 30/6 for residents seeking a cool space. Roads in some parts of Illinois have buckled due to the heat; when pavement lacks space to expand under continuous heat, it can heave and crack.

A woman wears a face covering to shield herself from the sun while cycling in Chicago's scorching weather.

Due to severe weather, Norristown, Pennsylvania, canceled its weekend Independence Day parade. Meanwhile, Philadelphia declared a heat emergency from 1/7 to 5/7, extending the operating hours of 50 cooling centers. The city also announced the setup of misting tents, hydration stations, and medical aid posts for attendees of the free World Cup fan festival at East Fairmount Park.