WASHINGTON • Americans braced themselves for a second - and equally scorching - day of dangerously hot weather yesterday, with daytime temperatures forecast to approach 38 deg C across a number of major US cities.
An oppressive heat wave stretching from the Midwestern plains to the Atlantic coast had nearly 150 million people searching for respite last Saturday.
"The temperatures we're seeing in our city today and tomorrow could be the highest we've seen in years. Take it seriously," New York City Mayor Bill de Blasio tweeted. He also declared a heat emergency.
The heatwave was expected to continue as a high-pressure system off the Atlantic coast ushered in steamy, subtropical air.
"Dangerously hot conditions will continue through Sunday," the National Weather Service (NWS) warned for the Washington and Baltimore area, where forecasters predicted high temperatures ranging from 35 to 38 deg C for a second day.
"High temperatures and humidity could quickly cause heat stress or heat stroke if precautions are not taken," the NWS added.
People were urged to stay hydrated, watch out for the sick and elderly, remain indoors and not leave children or animals in cars.
The heatwave has claimed at least three lives, including two in the eastern state of Maryland. In Arkansas, 32-year-old former NFL player Mitch Petrus died of heatstroke last Thursday after working outside his family's shop.
Heat warnings have also been issued for parts of eastern Canada.
In Washington, a popular weekly outdoor summer jazz concert at the National Gallery of Art Sculpture Garden was cancelled.
The New York City Triathlon, which had been scheduled for yesterday, was cancelled for the first time since its founding in 2001. And the two-day OZY Fest - a food, comedy and music festival set for Central Park - was also called off.
New York City opened 500 cooling centres for residents.
At least three public defenders said on Twitter that inmates in New York's notorious Rikers Island jail complex were suffering with no air conditioning, and that some guards had turned off fans as punishment, resulting in "deadly conditions".
The Brooklyn Defender Services legal aid group said some inmates did not have summer clothing, only long underwear provided by the group last winter.
Top officials from the city's Department of Corrections were at the facility monitoring the response to the heatwave to "protect health and safety of everyone in the facility", Mr de Blasio tweeted.
In Boston, where the weather service said Saturday and Sunday would be "major scorchers", entry fees at public pools were scrapped.
Earlier last week, the National Weather Service office in the Midwestern city of Omaha baked a tray of biscuits - breakfast bread similar to scones - on the dashboard of a parked car. After nearly eight hours and with temperatures on the pan reaching 85 deg C, the pastries were almost fully cooked.
Climate data shows June was the hottest month on record worldwide, with a heat wave across Europe smashing national records.