Foz do Iguaçu weather in May
May in Foz do Iguaçu: warm, soaked, with clean air — fine if you can take 11 rainy days.
Updated September 2026 · climate normals from ERA5 reanalysis
#5 of 12 months in Foz do Iguaçu · #940 of 1413 destinations to visit in May · comfort 74/100 (tier B)
- Days
- 25°C
- Nights
- 15°C
- Wet days
- 11
- Sun
- 7.5 h
- Humidity
- 80%
- Daylight
- 11 h

Traveller notes on Foz do Iguaçu in May
Notes from nearby Puerto Iguazú (6 km away)
Foz do Iguaçu doesn't have its own notes for May yet — these are about Puerto Iguazú, close enough to share the season.
Puerto Iguazu-forum threads on May weather call it a genuinely strong shoulder-season month, mild afternoons that stay comfortable for a full day of walking the falls trails without the intense heat of peak summer, though mornings and evenings can feel noticeably cooler. Posters are consistent this sits toward the drier stretch of the year, blue skies fairly likely though a shower on any given day can't be ruled out entirely. Regardless of the forecast, posters are unanimous that visitors get genuinely soaked at the main viewpoints and catwalks purely from spray off the falls themselves, ponchos or a three-dollar plastic cover sold locally standard advice either way. Water levels and crowd numbers are both called favorable in May compared to the busier peak holiday stretches. The record: 25.3C days feeling like 26C, 15C nights, 81 percent humidity and 6.9 hours of sun.
Other months in Foz do Iguaçu
Foz do Iguacu-forum threads on February weather describe this as genuinely hot and humid, posters calling the Brazilian side's panoramic walkway a real highlight for seeing the full sweep of the falls across the canyon. Regulars call water volume typically strong this time of year, the color sometimes running reddish-brown after heavy rain upstream, a natural effect rather than pollution. Posters describe the mist at several viewpoints as genuinely soaking, ponchos available for rent though many visitors accept getting wet. Regulars recommend a half day on the Brazilian side as sufficient, the Argentine side offering the more extensive trail network for a full day. Posters call a sudden afternoon thunderstorm a real possibility, checking the forecast that morning standing advice. Regulars recommend comfortable clothes regardless of which side you visit. The record: 32.9C days feeling like a punishing 38C, 21.8C nights, 115.5mm across nearly 12 days and 75 percent humidity.
Foz do Iguacu-forum threads naming the best months for the falls call March a genuinely strong pick, peak summer crowds thinning while water volume typically stays strong from the wetter months just behind. Posters describe daytime conditions as comfortably warm rather than punishing, evenings cool enough that air conditioning becomes unnecessary most nights. Regulars call the wetter pattern running November through early in the year as generally easing off by March, though a passing system remains possible. Posters recommend flexible plans, a shower rarely lasting long enough to disrupt a full day. Regulars describe visibility and mist as generally favorable this time of year, the full width of the falls usually clear from the main walkways. Posters call March one of the more comfortable months for the Brazilian side specifically. The record: 31.8C days feeling like a punishing 35C, 20.9C nights, an extraordinarily high 122.3mm across nearly 12 days and 76 percent humidity.
Foz do Iguacu-forum threads on September confirm this sits toward the start of a favorable stretch, comfortable temperatures and generally settled conditions on the Brazilian side of the falls compared to the more extreme months. Posters describe water levels as capable of swinging within the same week, one visitor reporting locals calling the river low and the falls comparatively dry just before arrival, only for an upstream system to bring the falls back to a misty, dramatic full flow by the time they visited. Regulars call this unpredictability part of the appeal, no two visits looking quite the same. The Brazilian side's panoramic walkway is repeatedly named the better overview compared to the closer, wetter Argentine trails, both sides commonly combined into a single trip. Posters call September crowds noticeably thinner than peak holiday periods. The record: 29.5C days feeling like a punishing 32C, 16.6C nights, 71 percent humidity and 7.1 hours of sun.
August sits at the end of the drier half of the year, and the forum's framing is a trade: sunshine most days, and falls that are not at their strongest, since the lowest water levels fall in July and August. How low depends on rain upriver rather than on the calendar, and the variance is wide - the same month has produced complaints of poor volume and reports that the falls were stunning regardless. The compensations regulars name are cooler air and easier walking on the trails. Our row supports the drier reading without making August dry: 94.1mm over 7.2 precipitation days. The record: 26.5C days, 13.9C nights, humidity 71 percent and 8.8 hours of sun.
Add your own note from Foz do Iguaçu's card on the map.
Foz do Iguaçu climate normals — May
Monthly averages from ERA5 reanalysis. AQI is the mean US Air Quality Index for the month.
Crowds in Foz do Iguaçu in May
How busy the place itself is — school and mass holidays, the months an editor tagged, and how sought-after the weather makes them. Never part of the comfort score.
Shoulder seasonan ordinary month(estimated)
Peak crowdsBusyShoulder seasonQuiet
Best months for Foz do Iguaçu's weather
Ranked by this destination's own climate comfort score across the year — a different thing from how busy it gets (see Crowds above).
Fair weatherFoz do Iguaçu's weather peaks June–August, best around July.
Best weatherFair weatherToughest weather
What's on in Foz do Iguaçu in May
Recurring seasonal events, natural spectacles, closures and holidays — curated and sourced.
- Rule
Timed park tickets, booked online
1 Jan – 31 DecBook earlyBoth sides sell entry by day and hour online and the Brazilian park caps arrivals per hour, so turning up without a slot in high season means waiting or missing it. Two countries, two tickets. Source ↗
Where is Foz do Iguaçu?
Foz do Iguaçu in May — FAQ
- Is May a good time to visit Foz do Iguaçu?
- May in Foz do Iguaçu: warm, soaked, with clean air — fine if you can take 11 rainy days. It ranks #5 of 12 months for Foz do Iguaçu on SeasonMap's comfort score (74/100).
- What is the weather like in Foz do Iguaçu in May?
- In May, Foz do Iguaçu averages a daily high of 25.2°C and a low of 15.3°C, with about 153.2 mm of rain over roughly 10.6 rainy days.
- What is the air quality in Foz do Iguaçu in May?
- Foz do Iguaçu has a mean US Air Quality Index of about 24 in May.