The National Weather Service on Monday issued a heat advisory for New York City on Tuesday and Wednesday, warning that temperatures could climb to 95 degrees Fahrenheit (35 degrees Celsius), with a heat index of up to 102 degrees Fahrenheit (38.9 degrees Celsius).
"We've battled the heat before -- we've gotten all kinds of weather here at the U.S. Open," U.S. Tennis Association spokesman Christian Widmaier said. "We've got cool nights; we've got hit by a hurricane."
Widmaier added that the tournament would advise fans to stay hydrated and seek shade as much as possible.
On Monday, it was clear that the heat was getting to some of the players.
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A first-round match between American Venus Williams and Russia's Svetlana Kuznetsova was halted for 10 minutes as the heat rule came into effect. At several points during the match, Williams was seen with an ice wrap around her neck.
Britain's Andy Murray also employed an ice wrap during breaks in play during his first-round match against James Duckworth.
The retractable roofs of Arthur Ashe Stadium and the newly- built Louis Armstrong Stadium only close in the event of precipitation, Widmaier said.
If temperatures reach a critical level by the start of singles matches, it can trigger the U.S. Open extreme weather policy, which permits an optional 10-minute break between the second and third sets for women; for men, breaks in play follow Grand Slam guidelines.
Of course, not every player minds.
Estonia's Kaia Kanepi, who stunned world number one Simona Halep in the first round, told reporters she thrives in New York's muggy summer heat.
(Reporting by Amy Tennery, editing by Ed Osmond)
