Colder destinations like Norway are becoming some of the most sought-after summer vacation sites.

As record-breaking heat waves happen with increasing frequency , more travelers are finding that traditional summer hot spots like Paris or even the Pacific Northwest hold the potential for a sweltering, sweaty trip. This has prompted tourists to seek cooler ground as they plan their vacations, travelers, analysts and tour operators say.

Places like Bergen, Norway, and Innsbruck, Austria, have been particularly sought after, say travel agents and tour operators. Both cities offer less intense summer weather, natural beauty and cultural experiences, without the crowds that mob still-popular destinations like Rome or Barcelona.

Bookings for trips to Norway between June and August are up 37% compared with a year ago, according to Kensington Tours, a global luxury-tour operator. This year, Norway ranked among the top 10 destinations in Europe in terms of booking volume after not making the list last year, says Jason Susinski , Kensington’s director of product. Bookings have also grown for Sweden and Finland, rising 70% and 126%, respectively.

Mary Miles , a 33-year-old Baltimore resident who works in public relations, makes an effort to go on one big international trip a year with her husband. Their travels have taken them everywhere from France and Italy to Thailand and Japan.

This September, the couple will endeavor on a trek across Scandinavia, visiting Norway, Sweden and Denmark over two weeks.

Miles has long dreamed of visiting the region, having grown up hearing tales of her mother’s time in Sweden during a foreign-exchange program. For her husband, the weather is one of the biggest perks.

“He’s very, very sensitive to heat,” she says, adding that he gets dehydrated easily. “He gets nervous that he’s going to pass out.”

The cold push

Travelers have searched for significantly more trips from U.S. airports to both domestic and international destinations that have cooler climates in 2024 compared with last year, according to search site Kayak.

Flight searches to Southampton, England, where the average high in the coastal city between June and August ranges from 69 to 73 degrees, rose by 57% over the past year. Searches for Fairbanks, Alaska, were up 25%.

An analysis by travel booking company Hopper found that the two European destinations that have recorded the largest percent increase in search demand for the summer months compared with both last year and 2019 were the Faeroe Islands and the Czech Republic.

“As Europe braces for the impact of increasingly common extreme weather events, we anticipate travel patterns and destination choice shifts over the long term,” says Eduardo Santander , executive director of the European Travel Commission, a Brussels-based association of national tourism organizations.

Greece is among the destinations that have coped with harsh wildfires along with the heat in recent years.

Travelers like Amy Deters are helping drive this shift to cooler places, in large part because of a recent poor experience.

She visited France last September with her husband and two adult children. Between booking flights and reserving times to tour sites like the Louvre, Deters didn’t think to check whether the family’s Airbnb in Paris’s second arrondissement had air conditioning.

It didn’t, as the Deters discovered when their trip coincided with unseasonably warm weather. Nor did many other places they visited in France. To beat the heat, the family resorted to buying lighter clothing, riding the Metro instead of walking and taking extra showers during the day to cool off.

“It was hot the entire week,” says Deters, a 60-year-old resident of suburban St. Louis. “There was not a reprieve.”

Surging Scandinavia

The strong demand for Nordic getaways has prompted some tour companies to increase their offerings in the region.

Abercrombie & Kent, a luxury-travel company that sells small-group tours and plans private vacations, is launching a new fjord-themed tour of Norway and Denmark this year. The 10-day itinerary includes stops in Oslo and Copenhagen, cruises around fjords and an experience in a Viking-inspired village.

Of the eight iterations of the tour planned for this summer, seven have already sold out, according to Liam Dunch , Abercrombie & Kent’s global group product manager for Europe.

Pleasant summertime weather isn’t the only draw for Scandinavia. In the winters, its climate is more reliably cold compared with many ski resorts across the globe, cementing the region’s status as a winter-sports powerhouse, travel agents say. The colder months are also a prime time for viewing the Northern Lights.

Spring and fall are also popular, says Anette Karlsson , chief executive of Oslo travel company Authentic Scandinavia. May is particularly sought after as melting snow creates massive waterfalls across the country and feeds blooming flowers, she says.

Beyond the natural wonders, people are also attracted to the cuisine and architecture in cities like Stockholm, Susinski says.

Aside from going north, some tourists are opting to go well below the equator to take advantage of the Southern Hemisphere’s winter months. That has led to growing interest in places like Patagonia and New Zealand, travel companies say.

Other jet-setters are heading for the hills—literally. Italy is perennially a tourism hot spot, but that doesn’t mean that a trip there has to be literally hot.

Bookings with Kensington Tours for go-to Italian locations like Rome, Florence and Venice are up 22% over the past year. Como, near the Swiss border, notched even bigger gains, with bookings up 64%.

“We are definitely seeing more rural destinations increase, as well in our most popular countries,” Susinski says.

Write to Jacob Passy at jacob.passy@wsj.com