Best Time to Visit Foz do Iguaçu: Waterfall Flow, Seasons and Full Moon Walks

Because the 1,320-kilometre-long Iguaçu River drains a vast subtropical watershed across Paraná and Santa Catarina states that receives rainfall throughout the year, Iguaçu Falls flows powerfully in every month of the calendar, averaging roughly 1,500 cubic metres of water per second. According to official World Meteorological Organization (WMO) and INMET 1991 to 2020 normals recorded at Foz do Iguaçu Aeroporto (Station 83827), the city has a humid subtropical climate (Köppen Cfa) with warm summers, mild winters, and 6 to 11 rain days per month.

March to May (Autumn) and August to October (Spring): Best Overall Balance

For most travellers, the two shoulder windows of March to May (austral autumn) and August to October (austral spring) offer the most comfortable combination of pleasant walking temperatures, strong waterfall volume, and clear photography skies:

• Temperatures and rainfall: Afternoon highs ease from 30.2°C in March to 27.6°C in April and 23.8°C in May (with 8 to 9 rain days per month), while spring warms from 25.4°C in August and 27.1°C in September to 29.0°C in October.
• Why visit now: You avoid the intense midday heat and school holiday crowds of January and July while enjoying full river volume on both the Brazilian and Argentine boardwalks, as well as active birdlife inside Parque das Aves.

December to February (Austral Summer): Thunderous Peak Water Volume

During the southern hemisphere summer from December through February, daytime highs average 31.2°C to 31.5°C with warm nights around 20.8°C and frequent late-afternoon tropical showers (10 to 11 rain days per month). Upstream rains swell the Iguaçu River to its most dramatic volume, turning the 275 cascades into a continuous roaring wall of white water and cooling spray, and often prompting Itaipu Binacional to open its giant spillway chutes.

June to August (Austral Winter): Mild Days and Lowest Rainfall

From June to August, Foz do Iguaçu experiences its coolest and driest months, averaging just 6 to 8 rain days per month. Afternoon temperatures reach a comfortable 22.4°C in June, 22.9°C in July, and 25.4°C in August, while early mornings dip to 12.1°C to 13.5°C. Pack a light fleece or windbreaker for 08:00 park departures and for the breezy boat ride on the Macuco Safari.

Monthly Full Moon Walks (Luau das Cataratas)

When timing your trip, check the lunar calendar: on five consecutive nights around each month's full moon, both the Brazilian and Argentine national parks host guided after-hours evening walks to the edge of the falls, where bright moonlight refracting through the rising canyon mist creates a rare silver lunar rainbow (arco-íris lunar).