The coastal fog (Spanish: Camanchaca) hangs on the mountain-slopes and moistens subtropical vegetation, allowing the hydrophilic forests to survive despite being surrounded by semiarid scrublands, with average annual rainfall of approximately 113 mm.

Many different kinds of birds live in the park, such as the Chilean tinamou (Nothoprocta perdicaria) and the long-tailed meadowlark (Sturnella loyca).

The place where today the Fray Jorge National Park is located was discovered in 1627 by a priest of the Franciscan order, who, due to a lack of timber in the area, set out to search for it with the help of some mules.

After "miraculously" finding it at this location, he brought back some timber and used it to build part of the bell tower of the Church of San Francisco in La Serena.

Phylogeography of Plectostylus Beck, 1837 (Gastropoda: Stylommatophora: Orthalicoidea): Origin and isolation of the Fray Jorge forest relicts in northern Chile Article in Journal of Zoological Systematics and Evolutionary Research 57(1) DOI: 10.1111/jzs.12242