US braces for ‘dangerous’ conditions as heatwave to hit midwest and north-east

Millions of Americans are facing “dangerously hot conditions”, the National Weather Service said, with a heatwave set to hit the midwest and north-east US from Monday.

Michigan, Ohio and western Pennsylvania were all under heat warnings starting Monday, with alerts in place until Friday evening. Meteorologists warned that the heat will spread east through the week, with a “heat dome” expected to trap high temperatures across New York, Washington DC and Boston.

The warnings come as states in the south were experiencing higher than usual temperatures on Sunday. Phoenix, in Arizona, was under a heat warning, with temperatures expected to reach 110F (43C), while officials in Atlanta, Georgia, opened a cooling center over the weekend as temperatures reached 100F.

The NWS said an excessive heat watch will be in place over north-east Indiana, western Pennsylvania and most of Michigan and Ohio from Monday. It warned people to expect “dangerously hot conditions”, with heat index values of 100F (38C) or higher likely.

The heat index, or apparent temperature, combines the air temperature with humidity to calculate what heat feels like to the human body.

People in those areas should drink plenty of fluids, avoid the sun, and stay in air-conditioned rooms, the NWS said. It warned that drivers should avoid leaving children or pets in unattended vehicles, as car interiors “will reach lethal temperatures in a matter of minutes”.

Detroit, Michigan, is likely to see its worst heatwave in 20 years, the Associated Press reported. Monday is expected to see heat indices of 100F, which will last through the week.

Ohio’s governor, Mike DeWine, said residents should “check on older neighbors, and have a plan if the heat becomes too much”, the Ironton Tribune reported. The emergency management authority for Delaware county, in the center of the state, published a list of “cooling centers” where people can escape the heat.

New York City and other parts of the state are expected to see heat index temperatures of up to 105F (41C) in the coming week. Governor Kathy Hochul said people should “take every precaution they can” over the coming week – including bracing for severe thunderstorms which are expected to hit on Friday.

A heat dome is expected to prolong the extreme heat. A heat dome occurs when high pressure traps hot air over a region, causing temperatures on the ground to rise further.

While some areas will see cooler temperatures at night, there will be areas of extreme heat, with little or no overnight relief, from eastern Kansas to Maine, according to a National Weather Service heat risk map.

It comes as authorities evacuated at least 1,200 people in Los Angeles county on Saturday, as a wildfire spread over thousands of acres near a major highway and threatened nearby structures.

Experts say that the climate crisis, triggered by burning fossil fuels and deforestation, will increase the number of devastating heatwaves around the world.

In 2023, the hottest year on record for the planet, the US had the most heatwaves – abnormally hot weather lasting more than two days – since 1936. In the south and south-west, last year was the worst on record, according to the National Oceanic and Atmospheric Administration.

Last year a report by Climate Central, an environmental non-profit organization, found that a total of 175 of the 244 US cities analyzed had at least one week with extraordinarily warm temperatures.

Heat-related deaths have increased in the US in each of the last three years, according to the Department of Health and Human Services. There were 1,602 such deaths in 2021; 1,722 in 2022; and 2,302 in 2023.