A searing heatwave brought summer misery to the American heartland, enveloping as many as 17 US states in oppressive temperatures and humidity likely to persist into next week, forecasters said Tuesday.
US officials said there had been at least 13 deaths across the United States as a result of the intense and persistent heat, as the central United States sees a string of days with temperatures topping 100 degrees Fahrenheit (37.7 Celsius).
The heat has been coupled with near record humidity - a miserable combination that forecasters said would move eastward in the coming days.
"A combination of very hot temperatures and high humidity will created dangerous heat indices over the central US," said the National Oceanic and Atmospheric Administration (NOAA).
A spokesman with the National Weather Service meanwhile told AFP that more than a thousand heat records had been broken across the United States in just the past month.
The intense high temperatures are reported to have caused roads in the southern plains state to buckle, while dozens of people required medical treatment, according to the Daily Oklahoman newspaper, which reported that Oklahoma City saw its 28th day of triple-digit temperatures this year Monday.
The central US states of Illinois and Indiana were expecting temperatures and humidity indices above 115 Fahrenheit (46 Celsius) with even worse weather predicted in some areas by Thursday.
The US east coast already on Tuesday was beginning to feel the effects of the oppressive weather, which was expected to reach New York, Washington DC and the rest of the eastern seaboard full force by midweek, according to NOAA.