How Crowded Is Castillo de San Marcos in December?
December is a busy month at Castillo de San Marcos National Monument, running about 1.2× the park's average month — roughly 10% of the year's visitors come in December. That puts it between the March peak and the September low. Overall our best-time score rates December as "Fair" for a visit. Typical December weather averages a high near 69°F and a low around 51°F, with about 3" of precipitation. You'll get about 10.1 hours of daylight to explore.
Frequently Asked Questions
December is busy at Castillo de San Marcos National Monument (about 1.2× the average month). Our best-time score rates it "Fair". The single best month overall is October.
The busiest month is March and the quietest is September. December sits at about 1.2× the park's average, or 10% of annual visitation.
Source: National Park Service Visitor Use Statistics (1979–2025), NOAA NCEI Climate Normals 1991–2020. Updated 2026-06-20.