September marks a change of seasons in the southern hemisphere as winter turns to spring. In the region of southern Brazil and northern Argentina, where Iguazú Falls are located, that means slightly longer days, warmer temperatures, and more rainfall, particularly as the month rolls on: this is the end of the dry season that extends through the winter, too.
Expect highs in the upper 70s and lows in the upper 50s, with moderate humidity—great weather for hiking, as it's not too hot during the day. An occasional rainy day or spring storm passes through at this time, so consider bringing a raincoat. Days are starting to get a bit longer as spring begins, especially later in September, so take advantage of having more time to enjoy being outdoors.
Crowds & Costs
In comparison with some other months, Iguazu doesn't see huge numbers of international or domestic tourists in September. School is in session in Argentina and Brazil, meaning fewer families are traveling in the region—save for weekends!—and since September, weather-wise, is an ideal time to travel throughout many parts of the northern hemisphere, fewer visitors from other parts of the world are here.
All of this is good news if you're planning a trip to Iguazú Falls in September. It's still smart to plan ahead with plane tickets and hotel reservations, but you can be a bit more spontaneous at this time of year, possibly even taking advantage of mid-week promotions and discounts at hotels. In the park, you'll encounter plenty of weekenders and tourists on longer itineraries in South America; it's a good idea to reserve a rental car ahead of time, too, if you need one.
What To Do
Since you're visiting during a relatively quiet time at Iguazú, it's a good time for quiet hikes, bird-watching, and photo ops. Go on a thrilling boat ride to the base of the falls on the Gran Aventura excursion or raft on a quieter section of the river on the Ecological Trip ride that's offered by the same tour operator—information on both options is available online and at the Visitors Center.
Explore the manmade catwalks around the waterfalls' cascades and bird-watch in the forest, stopping at viewing platforms and lookout points along the way, where you'll enjoy relatively unobstructed views of key natural attractions like Bossetti Jump and Garganta del Diablo.
If you really want to get away from it all, consider the round-trip trek to a small waterfall on Macuco Trail, where most visitors never venture. Bring a picnic, a swimsuit, and mosquito repellant: it may be the end of winter and start of spring, but you're still in the jungle.
What To Look For
Though you're not especially likely to see a jaguar at Iguazú, it's not out of the question in September: when the parks aren't overcrowded with tourists, the forests' inhabitants are more active than usual. Jaguars eat birds, frogs, foxes, deer, fish, and monkeys, among other animals—and they're attracted to water sources, swimming in rivers and streams—so keep your eyes open as you're walking in quieter sections of the parks.
The region is also home to hundreds of species of birds, including colorful toucans, hummingbirds, doves, cuckoos, and parakeets. You'll also see howler and capuchin monkeys—like the raccoon-like coati, they like to congregate at concession areas in the park, where they can feast on leftovers of sandwiches and other snacks, so hold on tightly to your picnic lunch—plus the capybara, also known as largest rodent in the world.
Apart from wildlife, Iguazú's many forested trails are wonderful to explore at this time of year. This is the end of the dry season, and although the rush of the waterfalls isn't as spectacular as it is in summer, catwalks and trails stay dry and easily navigable, which is a nice perk if you're traveling with children.
Events & Activities
Walks in the Moonlight: Iguazú National Park offers guided nocturnal tours on five evenings each month. The schedule depends on the lunar calendar. Sign up ahead of time for the chance to see the park’s natural attractions under the moonlight, plus owls and other creatures that only come out at night. Several departures are available (7:45, 8:30, and 9:15pm) and reservations are required.
Visiting Iguazú Falls in September? Check out these itineraries.
Buenos Aires & Iguazú Falls Experience - 7 Days Begin your journey in Buenos Aires and head to Iguazú Falls to see the jaw-dropping beauty of the largest waterfall system in the world. You'll get to experience the falls from both Argentina and Brazil, and take in a tango show in the capital city.
Ultimate Iguazú Falls Experience - 4 Days This four-day getaway to Iguazú Falls takes you into the heart of one of Argentina’s most prized destinations. Then, you'll experience another side of the falls from Brazil, with expansive, panoramic views.