'Dangerous heat wave' takes hold in East, Central US

Americans from Texas to Maine sweated out a steamy day today as a heat wave cancelled events from festivals to horse races and pushed New York City to order power-saving steps to avoid overtaxing the electrical grid.

The National Weather Service said "a dangerous heat wave" was expected to break record highs in some places, particularly for nighttime. Daytime temperatures were poised to hit about 34 to 37 degrees Celsius, with high humidity making it feel considerably hotter.

"It's brutal," Jeffrey Glickman said as he paused during a run today in Washington.

The 37-year-old got out early to try to escape the worst heat but still planned to cut his route short on an already 32-degree Celsius morning.

"You just have to power through it the best you can," he said.

Many places facing excessive heat this weekend have no air conditioning, with cities opening shelters for people to cool off. While the Midwest will get some relief tomorrow as a cold front moves in, the East isn't so lucky, the weather service warned.

New York City authorities cancelled a Times Square commemoration of the 1969 moon landing and an outdoor festival featuring soccer star Megan Rapinoe, musician John Legend and Daily Show host Trevor Noah.

The city also directed owners of many office buildings to set thermostats no lower than 26 degrees Celsius through tomorrow to reduce strain on the electrical grid.

In Chicago, heat forced organisers of the Humana Rock 'n' Roll Marathon series to cancel one of three weekend races. Today's 5K is off, but a 10K and half marathon are expected to go ahead tomorrow.

In New Jersey, operators of the Monmouth Park horse racing track were considering whether to push back the NZ$1.47 million Haskell Invitational later in the evening. Maximum Security, the horse that crossed the finish line first in this year's Kentucky Derby and then was disqualified, was among those scheduled to run.

Amid pressure over a series of horse deaths in California, several tracks have cancelled today's races, including Saratoga Race Course and Finger Lakes in New York and Laurel Park in Maryland.

At Yankee Stadium, where the home team was set to face the Colorado Rockies, extra hydration stations were set up in all three decks and the bleachers. Announcements reminded fans to keep drinking water.

Yankees manager Aaron Boone said he was mindful of the heat, too. "You tend to monitor guys a little more closely, want to see how your pitchers are doing," he said.

Europe, too, has been experiencing extreme heat waves in recent weeks. In France, thousands of schools were closed and outdoor events were cancelled after reaching a record high of 45.9 degrees last month.