Demand for summer flights soar: When to buy flights domestically, internationally to save

Airlines are already booking up for getaways abroad this summer and as Americans finalize travel plans, there are some important things to keep in mind.

With 75% of seats already sold on their aircrafts, Delta revealed that it has had to increase its number of international flights.

As search interest soars for summer travel, Expedia travel expert Melanie Fish told "Good Morning America" that their app has already seen "a 25% jump in flight searches over the summer" for popular domestic destinations alone, such as Los Angeles, Seattle and New York City.

"People are going back to cities, but we're also seeing people interested in these more far-flung destinations," Fish said.

June will likely mark peak prices for domestic travel and July for international destinations.

Hayley Berg, an economist for the travel booking app Hopper, told "GMA" that for anyone planning to travel domestically, "book now if you're going to be traveling in May, June or July."

"If you're planning to travel at the end of the summer, think August, early September and Labor Day," Berg said. "You have a few more weeks to find the best deals."

London, Paris, New Zealand, Japan and Vietnam are among the most popular international destinations. But Berg suggested finding cheaper destinations or nearby arrival cities for less.

"Most travelers headed to a bucket list vacation in Europe are going to consider the big cities Rome, Paris, London," she said. "But Portugal is typically very inexpensive to fly in and out of."

Bianca Signez plans to take her first international trip since the onset of the COVID-19 pandemic. But she told "GMA" that increased airfare alone for peak summer travel has already left her "really disappointed."

"I hear that July is a great time to go to Italy, which I'm excited about, but it's also very pricey," Signez said. "The flight alone will cost me a little over $1,000 -- I think that's the most I've ever spent on a flight before."

As airfare prices trend upwards, another option to get more bang for the buck could be to head for the high seas instead.

Cruise Critic shows that you can travel to Alaska between May and August for less than $115 per night per person, with some ships selling spots as low as $37. Meanwhile, average fares for cruises to Mexico are less than $100 per night for most of the summer.

When it comes time to plan domestic travel, experts suggested booking airfare 21 to 60 days out and at least three months in advance for international airfare.

Last year, average ticket prices were around 8% lower during these same time frames, compared to 60 to 90 days out.