Temperatures nearing 40C and high humidity leave 22 dead, fill hospital emergency rooms and exacerbate midwest drought A stifling US heatwave which has left at least 22 people dead and set dozens of all-time local temperature records is moving east across the country, bringing temperatures approaching 40C along with high humidity. The US National Weather Service had hot weather warnings in place for large sections of the country’s centre and east. The so-called heat index, a calculation of how warm it feels through the combination of temperature and humidity, exceeded 120F (49C) in parts of the midwest over recent days, with similar conditions expected into the weekend. “The combination of prolonged high levels of temperature and humidity will cause a potentially dangerous public health situation through Saturday,” the service warned on its website . On Wednesday, 55 different places saw record high temperatures, with another 60 all-time highs matched, the service said. It has blamed at least 22 deaths on the heatwave, many of them of older people. Ohio’s health department said hospital emergency rooms had been three to four times busier than normal due to cases of heatstroke and heat exhaustion. The heatwave has also reached the big cities of the east coast, with both New York and Washington DC expected to experience temperatures of around 38C or 39C over the next couple of days – bringing thousands flocking to swimming pools or coastal areas – before the mercury dips to a relatively tepid 30C. “Do not take this threat lightly,” the National Weather Service warned. “The length of this heatwave will pose a very real and dangerous health risk to at-risk groups and those that do not have access to air conditioning.” During the weekend the heatwave is expected to cover half the US. Many in the midwest have flocked to air-conditioned shopping malls or cinemas. Massive air conditioner use in southern Michigan on Thursday saw thousands of homes lose power, forcing officials to move older people without electricity to cooled communal buildings. The heat has exacerbated an existing drought in the midwest crop belt, affecting areas in Iowa, Illinois, Wisconsin, Indiana, Ohio and Michigan, the US Drought Monitor said. Texas remains gripped by a particularly severe drought, with 75% of the state affected. United States Natural disasters and extreme weather Peter Walker guardian.co.uk