Southern Europe is baking, thanks to a relentless heat wave with temperatures breaking records across Italy, Spain and Greece. This extreme weather, coupled with one of the busiest tourist seasons in recent years, raises questions for travelers looking to enjoy their vacations while staying safe. Here’s what you need to know if you’re heading to Europe in the coming days, or are already there.

Italy, Spain and Greece are the countries most impacted by a high pressure “anticyclone,” which originated in North Africa, that’s causing the record heat. Temperatures as high as 118 degrees Fahrenheit (close to 48 degrees Celsius) are possible later this week in Sicily and Sardinia; northeastern Spain saw highs of 115 degrees this week, while parts of central Greece hit 109 degrees. The hot, dry conditions have also exacerbated wildfires in Greece, Croatia, Switzerland and Spain’s Canary Islands, forcing thousands to evacuate.

Forecasts show the heat wave lasting for at least another week, through the end of July. However, this particular anticyclone — named Charon, for the ferryman for the dead in Greek mythology — follows closely on the heels of another high pressure system from the Sahara. (That one was called Cerberus, after the three-headed dog that guards the underworld.)

In general, European cities are poorly equipped to cope with extreme, persistent heat. Many have ancient architecture, particularly in areas attractive to tourists, and fewer buildings overall are equipped with air conditioning. According to a 2018 study, just one in 10 European households have air conditioning, compared to 90 percent in the United States. Some European countries have passed laws drastically limiting air-conditioner installation.

While some cities, like Paris, have worked to plant more trees and set up public cooling centers, experts say that these efforts have fallen short. A report published last week in the journal Nature Medicine attributed 61,000 excess deaths across the continent to last year’s heat waves; a worker in Northern Italy collapsed and died from exposure last week.

Safety is largely an individual question, dependent on your age, underlying illnesses and physical conditions. Regardless, extreme heat comes with decided risks. You can and should take steps to mitigate your risk.

Dr. Myhanh Nguyen, the department chair of travel medicine clinics for the Sutter Health Palo Alto Medical Foundation, advised travelers to know their medical history and any pre-existing conditions or medications that could lead to heightened heat sensitivity; she noted that infants and older people are particularly sensitive.

Speak to your doctor, or a doctor at a travel health clinic, before your trip, about any precautions. Then while traveling, consider your clothing, accommodations and daily activities.

“It’s important for everyone to reduce the risk of heat-related illness through protective behaviors,” said Claudia Brown, a health scientist with the Center for Disease Control’s Climate and Health Program at the National Center for Environmental Health. As for how to reduce that risk, Ms. Brown said that finding an air-conditioned environment, when available, is the most effective method.

“Beyond air conditioning, limit your outdoor activity, especially midafternoon, the hottest part of the day, and avoid direct sunlight,” Ms. Brown suggested. “Wear loose, light-fitting clothing, stay hydrated and take cold showers or baths to lower your body temperature.”

Dr. Nguyen also said staying hydrated is key.

“It’s important to not just orally hydrate, but to have an external source of water too, like a water fountain or swimming pool.” Dr. Nguyen also suggested paying close attention to any kind of official notices or warning systems, and avoiding dense, crowded attractions and seeking out shaded or wooded areas.

Be aware of the symptoms of heat exhaustion and heat stroke, and be sure to wear plenty of sunscreen.

At present, most travel insurance policies do not have specific clauses covering extreme heat, according to Beth Godlin, the president of the Aon Affinity Travel Practice, a travel insurance provider.

“Cancel for any reason policies will allow you to cancel based on the weather, as do newer policies that allow you to interrupt your trip for any reason,” she said. But aside from that, don’t count on your travel insurance to cover heat. Policies may cover emergency care for heat-related illness, such as heat stroke or dehydration, but even then, the coverage is for the resulting illness, versus the heat itself.

“Travel insurance policies have evolved, and this may become something that’s covered in the next couple of years,” Ms. Godlin said. “It’s not exactly an established phenomenon.”

In general, this summer’s crowded conditions in Europe leave little room for last-minute changes or cancellations that will be reimbursed, explained Joyce Falcone, president of the Italian Concierge, a New Jersey-based travel agency that specializes in trips and tours in Italy.

Ms. Falcone mentioned that many of her clients were hoping to stay on the Italian coast instead of traveling to steamy cities. But travelers canceling tours, drivers, hotels and more last minute should not expect refunds.

“Vendors are scheduled very tightly and don’t have much maneuverability,” Ms. Falcone said. “They’re trying to make a living, and have limited time to do so.”

“They go to the beach!” Ms. Falcone says. “They’re like New Yorkers who abandon the city and head to the Jersey Shore or the Hamptons.”

While not all Europeans are able to flee the city for the beach, many decamp for the country to relatives’ homes to escape the oppressive concrete of urban environments.

So you’re stuck in the city. Try to limit your wanderings to the early morning hours, before 10 a.m., or after the sun has set. Plan on a Spanish-style siesta during the hottest parts of the day. Underground attractions, like the catacombs in Rome, or the Civil War-era tunnels in Barcelona, are cooler alternatives to explore. Look into going to the movies, which tend to be air-conditioned. And while it may be too late this year, consider visiting the mountains in summer months or, better yet, avoiding summer travel altogether.

“Off season travel is the way to go,” said Ms. Falcone. “There are fewer crowds, and cooler weather. Take this opportunity to consider November, December, January or February. Italy is wonderful that time of year.”

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