Castillo de San Marcos National Monument in May
May at Castillo de San Marcos National Monument averages a daytime high near 85°F and an overnight low around 67°F, with about 3.7" of precipitation. Visitation runs about 1× the park's average month, which makes May an average month here.
- Average low
- 67°F
- Average high
- 85°F
Range across the year: 48°F to 91°F
- Precipitation
- 3.7 in
- Daylight
- 13.5 hours
Roughly 8% of the park's yearly visitors come in May: about 52,000 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 March peak (1.5×) and the September low (0.6×).
On our Best Time to Visit score May rates 64/100 ("Good"). Our recommended month is October: pleasant weather with noticeably thinner crowds (shoulder season).
The daily average of about 76°F is warm enough that midday heat is worth planning around. These figures are 1991–2020 NOAA climate normals from the nearest station, about 1.5 miles from the park.
Because June, July and August together draw about 24% 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 13.5 hours of daylight in May to explore — between the 10.1-hour midwinter low and the 13.9-hour summer high.
Park-wide, 2025 drew 598,070 recreation visits, up 3.1% from 579,825 in 2024.
Across the past decade overall visitation has eased about 13.4%, so May may feel a touch quieter than it once did.
How May compares with the months around it
| Month | Avg high / low | Crowds | Best-time score |
|---|---|---|---|
| April | 80°F / 61°F | 1.2× Busy | 62 Good |
| May | 85°F / 67°F | 1.0× Average | 64 Good |
| June | 89°F / 72°F | 1.0× Average | 48 Fair |
All twelve months at Castillo de San Marcos, with the best time to visit.
Frequently Asked Questions
May averages a daytime high near 85°F and an overnight low around 67°F at Castillo de San Marcos National Monument, with about 3.7 inches of precipitation. These are 1991–2020 NOAA climate normals from the nearest station, about 1.5 miles from the park, so conditions inside the park can differ, especially at other elevations.
May is average at Castillo de San Marcos National Monument (about 1.0× the average month). Our best-time score rates it "Good" at 64/100. Our recommended month is October.
The busiest month is March and the quietest is September. May sits at about 1.0× the park's average, or 8% of annual visitation.
A typical May sees about 52,000 recreation visits at Castillo de San Marcos National Monument, based on National Park Service monthly counts from 1979–2025.
Where to stay near Castillo de San Marcos in May
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Top-rated places to stay near Castillo de San Marcos
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Source: National Park Service Visitor Use Statistics (1979–2025), NOAA NCEI Climate Normals 1991–2020. Updated 2026-10-11.