The weeks between spring break and summer can feel like a lull to many travelers, but it's actually one of the best times to go on that big international trip.

Spring shoulder season, arriving in April and May, brings lower prices and fewer crowds before the peak summer rush sets in. Travelers can enjoy cheap airfare along with a more relaxed atmosphere at some of the top destinations. (For many places, you'll also score temperate weather as the sweltering summer heat has yet to hit.)

This year, spring shoulder season could save travelers up to 30%, with price drops between $250 and $380 to popular international destinations, according to Kayla Inserra DeLoache, KAYAK’s consumer travel trends expert.

Here's another bonus of traveling during the off-season: It also makes you a more sustainable traveler. Going when there are no crowds means you won't be joining the hordes of summer tourists overwhelming a destination that may already be dealing with overtourism.

“For any travelers looking to book that summer trip and facing some sticker shock from popular destinations, I recommend widening your travel dates to spring or fall," said Laura Lindsay, global travel trends expert at Skyscanner. "The shoulder season can be a great way to stretch your budget and get amazing deals. Flexibility in travel booking, whether it’s travel dates, destinations, airports, or airlines, will always yield the best deals."

In recent years, Skyscanner has seen more travelers book summer vacations before peak season to beat the crowds.

Here are the best shoulder season deals, according to some of the top travel platforms:

Tokyo

This year, Japan is stealing the hearts of travelers who want to explore its ancient temples, delicious cuisine and tranquil onsens. (The favorable conversion rate for Americans doesn't hurt either.) Spring is an ideal time to visit, with a round trip flight from the U.S. costing $1,194, about 13% less than in June and July this year, according to Hopper.

London

London, during the spring, offers cooler temperatures and cheaper flights for travelers. Last year, the average airfare to London in April cost $581 and shot up to $718 in July, Skyscanner found.

This year, travelers can save up to 18% if they go during April or May instead of June and July, according to Hopper.

Paris

The City of Lights is one of the most romantic perennial destinations with endless gastronomy, history and art. Last April, the average flight cost to Paris was $518 in April but rose to $803 in July – an increase of 55%, according to Skyscanner.

Flights to Paris this April and May go for $768 compared to $939 during June and July, for a savings of 18%, according to Hopper.

Seoul

Seoul is another emerging destination for American travelers, with a 25% increase in lodging searches this spring, according to Expedia. Travelers can score up to 17% in flight savings if they book in April or May for flight costs of $1,326. In June and July, prices go up to $1,605, according to Hopper.

Rome

The Eternal City has been struggling with overtourism and crowding at its most popular destinations, prompting it to consider fixed time slots at sites like the Trevi Fountain. Visiting during shoulder season not only helps you avoid those peak summer crowds but leaves more money in your bank account. Last April, the average airfare to Rome was $658 and shot up to $982 in June, according to Skyscanner.

Hopper data shows that a round trip flight during April and May costs around $813, about 18% cheaper than the $988 airfare in June and July.

Athens

Spring travelers to Athens, Greece, can roam ancient ruins and indulge in fresh Mediterranean cuisine, all without breaking the bank. Last April, flights to Athens went for $869 on average, and reached $1,131 by June, according to Skyscanner.

Round trip airfare in April and May costs $861 for a savings of 21% compared to the summer, according to Hopper.

Taipei

Ancient temples, affordable street food, and modern skyscrapers comprise the bustling capital of Taiwan, and spring is one of the best times to visit. Travelers can score big savings during this shoulder season – a whopping 29% with airfare for April and May costing $971, Hopper data found.

Helsinki

The coastal capital of Finland seamlessly blends together modern architecture, sustainable living and historic landmarks, like the UNESCO World Heritage Site, Fortress Suomenlinna. According to KAYAK airfare between March and May, airfare is $793 on average, about 32% cheaper than in June to August.

Glasgow

Scotland's Glasgow is the ideal destination for travelers seeking out a vibrant arts and culture scene along with eye-catching gothic architecture. Although spring will be a bit chillier than summer, a visit before peak season can save travelers up to 32% on airfare, according to KAYAK. Flights between March and May are priced at $854 on average before rising to $1,129 from June to August.

Bali

Known for its beaches and spiritual atmosphere, Bali has long been enchanting travelers looking for solace. Spring shoulder season offers cheaper airfare without contributing to overtourism at the Indonesian destination. KAYAK data shows flights between March and May costing $1,335 on average, about 29% less than the $1,719 price tag for June to August airfare.