Castillo de San Marcos National Monument in August
August at Castillo de San Marcos National Monument averages a daytime high near 90°F and an overnight low around 74°F, with about 7.2" of precipitation. Visitation runs about 0.8× the park's average month, which makes August a quiet month here.
- Average low
- 74°F
- Average high
- 90°F
Range across the year: 48°F to 91°F
- Precipitation
- 7.2 in
- Daylight
- 13.1 hours
Roughly 6% of the park's yearly visitors come in August: about 41,000 recreation visits in a typical year, based on National Park Service monthly counts from 1979 to 2025.
That makes August the 10th-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 August rates 50/100 ("Fair"). Our recommended month is October: pleasant weather with noticeably thinner crowds (shoulder season).
The daily average of about 82°F is hot, with afternoons near 90°F to plan the day around. These figures are 1991–2020 NOAA climate normals from the nearest station, about 1.5 miles from the park.
August falls inside the park's busiest stretch: June, July and August together pull about 24% of the year's visitors, so a visit this month means sharing the park with the peak-season crowd.
You'll have about 13.1 hours of daylight in August 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 August may feel a touch quieter than it once did.
How August compares with the months around it
| Month | Avg high / low | Crowds | Best-time score |
|---|---|---|---|
| July | 91°F / 74°F | 1.2× Busy | 34 Poor |
| August | 90°F / 74°F | 0.8× Quiet | 50 Fair |
| September | 87°F / 73°F | 0.6× Quiet | 64 Good |
All twelve months at Castillo de San Marcos, with the best time to visit.
Frequently Asked Questions
August averages a daytime high near 90°F and an overnight low around 74°F at Castillo de San Marcos National Monument, with about 7.2 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.
August is quiet at Castillo de San Marcos National Monument (about 0.8× the average month). Our best-time score rates it "Fair" at 50/100. Our recommended month is October.
The busiest month is March and the quietest is September. August sits at about 0.8× the park's average, or 6% of annual visitation.
A typical August sees about 41,000 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 August
Booking a August trip to Castillo de San Marcos National Monument? Compare hotels, cabins and vacation rentals near the park with live August availability and prices.
Top-rated places to stay near Castillo de San Marcos
Prices for Oct 30–Nov 1, 4 adults. Change dates on the map below.
Availability and prices from Stay22 partners (Booking.com, Vrbo, Expedia). We may earn a commission from bookings, at no extra cost to you.
Visiting Castillo de San Marcos in August?
Get crowd forecasts and lodging deals for Castillo de San Marcos by email. No spam, unsubscribe anytime.
See the full ranking of the best national parks to visit in August.
Source: National Park Service Visitor Use Statistics (1979–2025), NOAA NCEI Climate Normals 1991–2020. Updated 2026-10-11.