How Crowded Is Effigy Mounds in August?
August is a busy month at Effigy Mounds National Monument, running about 1.6× the park's average month — roughly 13% of the year's visitors come in August. That puts it between the July peak and the December low. Overall our best-time score rates August as "Fair" for a visit. Typical August weather averages a high near 81°F and a low around 61°F, with about 4.2" of precipitation. You'll get about 13.8 hours of daylight to explore.
Frequently Asked Questions
August is busy at Effigy Mounds National Monument (about 1.6× the average month). Our best-time score rates it "Fair". The single best month overall is May.
The busiest month is July and the quietest is December. August sits at about 1.6× the park's average, or 13% of annual visitation.
Source: National Park Service Visitor Use Statistics (1979–2025), NOAA NCEI Climate Normals 1991–2020. Updated 2026-06-20.