Dangerous heatwave hits central and southern America.

Central and southern America are facing the worst heatwave in decades with temperatures soaring above 100F (37.7C), the National Weather Service has warned. There are excessive heat warnings in place across the Midwest, Ohio Valley, Mid-Atlantic and southern states, meaning maximum temperatures are expected to be 105F or higher for at least two days with night time air temperatures not dropping below 75F.

People are being warned to take precautions to prevent becoming seriously ill or even die and avoid outdoor activities in the afternoon or evening.

"It's just day after day. Merciless," said Jeff Masters, meteorology director of the private Weather Underground. "We don't often see this much of the country this hot for this length of time."

The heat index that combines temperatures and humidity could reach as much as 120F in some areas affecting at least 130 million Americans with ozone pollution levels also reportedly high in cities like New York.

"This type of heat can cause heat stroke if you don't take precautions, so be sure to drink plenty of water and if possible avoid being out in the sun between 10am-3pm," said Weatherbug meteorologist Andrew Rosenthal.