How Crowded Is Effigy Mounds National Monument in May?

May runs about 1.1× Effigy Mounds National Monument's average month, which makes it an average month here — roughly 9% of the park's yearly visitors come in May.

In a typical May the park sees roughly 5,300 recreation visits, based on National Park Service monthly counts from 1979 to 2025.

That makes May the 6th-busiest of the park's twelve months, sitting between the July peak (2×) and the December low (0.4×).

On our Best Time to Visit score May rates 63/100 ("Good") — the single best-rated month at Effigy Mounds, balancing crowds against weather and daylight.

Typical May weather, from 1991–2020 NOAA climate normals at the nearest station, averages a daytime high near 70°F and an overnight low around 48°F, with about 4.7" of precipitation.

That average of about 59°F is a comfortable range for hiking and being outdoors all day.

Because June, July and August together draw about 42% of annual visitors, choosing May instead steps outside that summer crush — the single biggest lever on how crowded the park feels.

You'll have about 14.5 hours of daylight in May to explore — between the 8.8-hour midwinter low and the 15.2-hour summer high.

Park-wide, 2025 drew 56,912 recreation visits, down 8.2% from 61,975 in 2024.

Across the past decade overall visitation has risen about 7.1%, so a May visit is likely to feel busier than it did a few years ago.