The temperatures at the US Open are sweltering. Here’s how to beat the heat.

On Wednesday, fans and players at the US Open will sweat in a sweltering heat that is expected to reach 34 degrees.

The heat index—a measure of how the temperature actually feels when humidity is taken into account—is expected to reach 95-100. These conditions are so bad that the National Weather Service has issued a heat warning for New York City for most of the day.

A tournament spokesman did not respond to a request for comment on weather preparations Tuesday, but last year, under similar conditions, tournament organizers implemented a heat rule and partially closed the roof of Arthur Ashe Stadium on some days to provide additional shade.

The tournament website advises fans to start drinking early and continue drinking throughout the day. Breaks should be taken in cool indoor spaces such as shops or outdoors in places such as the tree-shaded seating area south of Arthur Ashe Stadium. People with heat-related illnesses should go to one of the first aid stations located throughout the National Tennis Center grounds.

A Newsday reporter measuring fieldside temperatures using a weather thermometer on Tuesday suggested another practical measure for fans: strategic seating selection.

During morning and early afternoon games, the south- and west-facing seats of many outdoor and arena courts were exposed to temperatures well over 100 degrees in full sun. Where there was shade, temperatures were often 10 degrees or more cooler. The north-facing seats of Court 17 were protected from the morning sun by the announcer’s booth and offered an unobstructed view of the baseline. As the day progressed, trees west of Court 14 and Court 4 cast shadows on some of those seats, as did the canopy over much of the stands.

Early Tuesday morning, Dr. Will Southern of Pleasantville, New York, took his seat high behind the south baseline on Court 17, saying he chose it for the shade and avoided the seemingly more desirable courtside seats. “You have to consider the arc of the sun – it’s not just moving sideways, it’s moving up,” he said. “If you come here in the middle of the day, everyone else is frying.”

Soon the seats around him were filling up. At the north end of the arena, baking had begun. In an area with seating for perhaps 100 spectators, nine were seated, including Marcus Latham. “I’m from England, mate,” he said. “We don’t get much sun, so I’m going to make the most of it.”

At around 2 p.m., when Caroline Wozniacki steamrolled a helpless first-round opponent on this court, Dr. Southern’s advice proved correct. The thermometer showed 42 degrees on the completely unprotected north side of the arena. On the south side, near his seat, the temperature quickly dropped to 32 degrees.

By 2:30 p.m., the thermometer on Court 4, where Matthew Forbes, an American elite junior, lost to Russian veteran Roman Safiullin, read 47 degrees in the blazing sun and dropped to 34 degrees in the shade of the trees. In a previous match on this court, players had worn ice packs around their necks during changeovers. Fans now lined up along a fence slightly higher than court level and crowded into the northwest corner of the bleachers at the baseline to avoid the sun. “There’s definitely a heat strategy,” said Ray Lira, 38, who works in retail and lives in Washington, D.C.

Lira said he started his day watching Chile’s Alejandro Tabilo and Belgian veteran David Goffin on the unshaded Court 11, but switched to the less prominent match for comfort. The heat was “insane,” he said.

Of all the outdoor courts, none are as brutal for the midday spectator as courts 8 through 16 on the north baseline, which are in full sun for most of the day and offer no shade. (There are no seats on the south baseline because of the layout of the tennis center.) The railings and uncovered seats on the north side felt like grilling hot. At midday, the thermometer read 46 degrees.

On Court 14, Darren Robinson, 53, a cybersecurity worker, and Samantha Robinson, 53, a scientist, had traveled from Sydney, Australia, to watch Australia’s Daria Saville lose a three-set, three-hour, nail-biting match to Ena Shibahara of Japan. “We knew the sun was going to shine, so we brought umbrellas,” Darren said. They also wore sunglasses. Perhaps because the Robinsons were sitting in the back row, ushers let them keep their umbrellas up throughout the match. After hours, the Robinsons did not appear tired. “There’s a breeze,” Samantha said. “It’s hot, but we’re OK.”