Effigy Mounds National Monument in May
May at Effigy Mounds National Monument averages a daytime high near 70°F and an overnight low around 48°F, with about 4.7" of precipitation. Visitation runs about 1.1× the park's average month, which makes May an average month here.
- Average low
- 48°F
- Average high
- 70°F
Range across the year: 10°F to 83°F
- Precipitation
- 4.7 in
- Daylight
- 14.5 hours
Roughly 9% of the park's yearly visitors come in May: roughly 5,300 recreation visits in a typical year, 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×).
May is our recommended month at Effigy Mounds: pleasant weather with noticeably thinner crowds (shoulder season).
The daily average of about 59°F is a comfortable range for hiking and being outdoors all day. These figures are 1991–2020 NOAA climate normals from the nearest station, about 3.7 miles from the park.
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.
How May compares with the months around it
| Month | Avg high / low | Crowds | Best-time score |
|---|---|---|---|
| April | 59°F / 37°F | 0.6× Quiet | 59 Fair |
| May | 70°F / 48°F | 1.1× Average | 63 Good |
| June | 80°F / 59°F | 1.5× Busy | 62 Good |
All twelve months at Effigy Mounds, with the best time to visit.
Frequently Asked Questions
May averages a daytime high near 70°F and an overnight low around 48°F at Effigy Mounds National Monument, with about 4.7 inches of precipitation. These are 1991–2020 NOAA climate normals from the nearest station, about 3.7 miles from the park, so conditions inside the park can differ, especially at other elevations.
May is average at Effigy Mounds National Monument (about 1.1× the average month). Our best-time score rates it "Good" at 63/100. May is our recommended month for this park.
The busiest month is July and the quietest is December. May sits at about 1.1× the park's average, or 9% of annual visitation.
A typical May sees about 5,000 recreation visits at Effigy Mounds National Monument, based on National Park Service monthly counts from 1979–2025.
Where to stay near Effigy Mounds in May
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Top-rated places to stay near Effigy Mounds
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See the full ranking of the best national parks to visit in May.
Source: National Park Service Visitor Use Statistics (1979–2025), NOAA NCEI Climate Normals 1991–2020. Updated 2026-10-11.