Summer starts Sunday. Here's how to stay cool when it gets hot.

Whether you are watching a World Cup match at jam-packed MetLife Stadium, stuck in body gridlock at Penn Station or braving a sweltering train platform traveling to July Fourth events — the heat is going to get you this summer.

But there are ways to fend off heat exhaustion, which can lead to dangerous heatstroke, according to some of Long Island’s emergency medicine specialists who regularly deal with heat-related illnesses.

Be prepared

"Plan ahead," said Dr. Christopher Caspers, chair of the department of emergency medicine at NYU Langone Hospital—Long Island. "Assume you're not going to have access to the usual remedies to the heat that you would normally have. You're not going to be inside air-conditioned areas that you would usually be in when it gets warm."

That means scoping out shaded areas, remembering to bring a hat and sunglasses to protect your face and eyes, wearing light-colored or moisture-wicking clothing, and drinking water or a beverage with electrolytes in advance of travel — and knowing where you can buy more.

Having a plan so you know what to do if you start feeling sick will give you quick access to relief when you need it, Caspers said.

Dr. Robert Schwaner, medical director of the department of emergency medicine at Stony Brook University Hospital, still remembers the heat at Giants Stadium during the 1994 World Cup match between Germany and Bulgaria that he attended with his brother and parents.

“When you are in a stadium, there aren’t many places to go,” Schwaner said, adding if you start to get a headache or feel nauseous, get out of the sun immediately and go to the shaded concession areas inside.

Stay hydrated

There are many beverages that will help you stay hydrated in the heat, Schwaner said. Beer is not one of them.

“Alcohol dehydrates you and makes it more likely for you to develop heat exhaustion,” he said.

Schwaner said World Cup fans should follow the example of the players and take hydration breaks throughout the game with water or beverages with electrolytes.

Caspers said drinking alcohol also makes it harder for people to recognize the symptoms of heat exhaustion until it’s too late.

“Alcohol is going to work against you in every way,” Caspers said. “If you are going to drink, do it in moderation and mix in some nonalcoholic beverages.”

Know the signs

Being aware of the signs of heat exhaustion could prevent you from developing the more dangerous condition of heatstroke.

The symptoms of heat exhaustion include fatigue, excessive sweating, dizziness and nausea. That’s the time to find a cooler spot, have cold drinks and use wet clothes on your skin to help cool down.

If a person stops sweating, then they could really be in trouble, Caspers said. That means their body can no longer cool itself down.

“When you're hot and dry, you should be thinking to yourself, 'I need attention,'" he said. “If you can't keep up with the fluids, you're starting to get nauseous or if people notice that you're a little bit confused, you feel disoriented, those are really signs of heatstroke.”

Keep an eye on others

Children, seniors and pets are especially vulnerable to the heat. Seniors may have medical conditions or be on medications that will mask the signs of dehydration, said Caspers.

A child's body temperature “rises three to five times faster than an adult’s,” and they cannot sweat enough to cool themselves down, according to the Columbia University Irving Medical Center. And pets need continuous access to clean water and a place to cool down. Many experts say pets should stay away from loud, crowded celebrations because they can get overheated and anxious from the noise and come in contact with foods that are toxic to them.

By Lisa L. Colangelo

lisa.colangelo@newsday.com@lisalcolangelo

Lisa joined Newsday as a staff writer in 2019. She previously worked at amNewYork, the New York Daily News and the Asbury Park Press covering politics, government and general assignment.