Laetitia Laurent, a South Florida interior designer, has long had her heart set on a Parisian pied-à-terre. This summer, with the dollar soaring and Parisian real-estate prices holding steady, she took the leap. The 42-year-old, who lives in Boca Raton, paid 758,000 euros, or $758,606, for a 460-square-foot, one-bedroom in the Golden Triangle—the prime residential and commercial area between the Seine and the Champs-Élysées, in the French capital’s pricey 8th arrondissement.

“I had been looking for a place for a long time,” says Ms. Laurent, who plans to use the apartment for work when she visits Paris to source designs for American clients, and for vacations with her husband and three young children. What helped propel her from just looking to outright buying was the strength of the U.S. dollar—“a huge factor” in the purchase, she says—15% over the past year, hovering at or near parity since mid-July. The dollar is rising so much, and so quickly, that Ms. Laurent estimates she saved around $80,000 between the time she first saw the apartment in early 2022 and when she closed in July.

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Taking advantage of the most favorable exchange rates in a generation, and reeling from exploding prices at home, buyers are disregarding other sources of instability—including the threat of coronavirus flare-ups, rising interest rates, travel disruptions, and the war in Ukraine—to sink their dollars into European residential real estate, with savings on luxury properties, compared with last year, reaching into seven figures.

Kate Everett-Allen, head of international residential research at London’s Knight Frank, identifies six European markets where American interest is now the most notable: London, Paris, Provence, Tuscany, northern Italy’s Lake Como and Lisbon.

With the exception of Lisbon—where prices rose 11.5% between the first quarter of 2021 and the first quarter of 2022—price gains in local currencies are modest to nonexistent in these markets. According to the most recent Knight Frank Global Residential Index, prices in greater London and Paris rose less than 5% between the first quarter of 2021 and the first quarter of 2022, while prices in Florence, Tuscany’s capital, dropped 1.6% during the same period. By comparison, America dominates the Knight Frank study, with nine of the top 20 spots held by U.S. cities. The top three, Phoenix, Miami and San Diego, have seen prices rise 29% or more. Ms. Everett-Allen points out that, though increases in both London and Paris are modest by American standards, they are both seeing their strongest performance in several years.

Ulrich Leuchtmann, head of foreign exchange and commodities research at Germany’s Commerzbank, says that the current parity between the euro and the dollar is actually somewhat deceptive—making the euro seem stronger than it is. Using the more relevant metric of real purchasing power, he says, “The euro is weaker than it’s ever been.” He credits America’s status as a net energy exporter and the Federal Reserve’s monetary policies with helping to strengthen the U.S. currency, and he puts part of the blame for the euro’s weakness on instabilities generated by the war in Ukraine.

Dollar-based buyers can expect the bargains to last. He is forecasting a short-term continuation of current exchange rates, with the euro staying just below the dollar through the end of the year.

The dollar is also soaring against the British pound, allowing London, Europe’s most expensive capital, to become even more attractive to a range of American buyers, says Rory McMullen, head of Savills’s North America desk in the real-estate company’s private office, which specializes in multimillion-pound listings. With the pound hovering around $1.15, the current exchange rate is offering the best opportunity in London for the dollar-based buyer since 2008, he says.

Mr. McMullen says Americans are looking for trophy homes in central London neighborhoods like Mayfair, Chelsea and Knightsbridge, and are generally less willing to look farther afield in more recently gentrified areas of the city that Londoners themselves might consider the height of luxury, such as Clerkenwell, near the traditional financial district, noted for its Victorian-era lofts.

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Savings on high-end London properties can seem mammoth. A 3,229-square-foot, four-bedroom, Savills-listed apartment in Knightsbridge has an asking price of £13 million, or $15.13 million. When it came on the market in mid-January of this year, the price, which has been the same in pounds since listing, was $16.4 million.

Even Americans with more modest budgets are taking notice. Robin Adkins, a Nashville-area business owner, has “fallen in love with Capri,” the Italian island off the coast of Naples. She says she has been thinking about buying for some time, and the new exchange rate means she has increased her budget from around €450,000 up to €500,000, which now converts to $500,000—enough for a starter apartment in high-altitude Anacapri, the island’s exclusive western community, known for its historic villas and hairpin-curve roads. The dollar’s strength has “definitely affected my search,” she says. 

Ms. Adkins’s agent, Capri-based Cristina Carrani of Engel & Völkers, says she is starting to see clients from the Pacific Northwest and the Midwest—a first, she adds, in her several years of selling homes on the island.

Elsewhere in Italy, American interest is way up in longtime favorite markets such as Lake Como and Tuscany, but is also finding its way to new areas, says Diletta Giorgolo Spinola, head of residential sales at Italy Sotheby’s International Realty. American second-home buyers are splurging everywhere from Puglia, in the heel of Italy’s boot, to the heart of Milan. She says sales of around $2 million are of greatest interest to her U.S. clients.

Once upon a time, American second-home buyers were eager to find romantic fixer-uppers in places like Tuscany and Umbria, but now, says Ms. Giorgolo Spinola, Italy-minded Americans are looking for turnkey properties “with few exceptions.”

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In the Lisbon area, Americans have established a conspicuous presence among buyers in Cascais and Estoril, the plush resort-like suburbs west of the city. Rafael Ascenso, founder and CEO of Porta da Frente, a Lisbon-area Christie’s affiliate, says that Americans now make up a larger portion of his agency’s clientele than any nationality other than native Portuguese and expatriate Brazilians, who have long made up the majority of buyers in the area.

Mr. Ascenso says Americans now have bigger budgets than the Portuguese speakers, with average sales in the €1.7 million, or $1.7 million, range for the first half of the year. Another local real-estate agent, Teresa Almeida Pinto, a sales manager at Portugal Sotheby’s International Realty’s Cascais office, says American buyers tend to break down into two categories: young digital nomads looking for walkability in the densely built-up resort centers, and retirees who may want access to golf courses further out along the Atlantic coast. “We get more and more Americans every day,” she says.

This recently renovated Victorian townhouse has up to eight bedrooms, six bathrooms and is 7,160 square feet. It is equipped with a new gym and media room, and it has views of the River Thames and a historic garden.

A lavishly furnished four-bed, four-bath turnkey duplex with a garden, in a late-19th-century building between the Champs-Élysées and the Seine, is 3,800 square feet. It has 14-foot stucco ceilings and has access to a private wine cellar.

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Located in the mountains south of Lucca, this 10,763-square-foot, five-bed, four-bath estate has a 17th-century villa on 9.88 acres with a walled garden and traces of an ancient Roman monument. The property includes a 2,150-square-foot, centuries-old farmhouse.