Muir Woods National Monument is located on Mount Tamalpais near the Pacific coast, in southwestern Marin County, California. It is part of the Golden Gate National Recreation Area, and is 12 miles north of San Francisco. It protects 554 acres of which 240 acres are old growth coast redwood (Sequoia sempervirens) forests, one of a few such stands remaining in the San Francisco Bay Area.
At Muir Woods, visitors are invited to step back in time to the days of one of the earliest park advocates. Walk among the soaring old growth coast redwoods, cooling their roots in the fresh water of Redwood Creek and lifting their crowns to reach the sun and fog. Federally protected as a National Monument since 1908, this primeval forest is both refuge and laboratory, revealing our relationship with the living landscape. Immerse yourself in the sights that inspired John Muir to be such a strong voice for the preservation and conservation of America’s most special places.
Muir Woods has a rich and varied history, from its use by the Coast Miwok people, to its early days of tourism and the Mount Tamalpais Mill Valley Scenic Railway, to an era of conservation, to modern preservation. In each era, the forest has been affected by the actions of humans, for better or for worse.
The incredible diversity of flora and fauna at Muir Woods can be daunting some times, elusive at other times. The redwoods themselves dominate the scene, but the Steller's jay often steals the show. Ladybugs clustering by the thousands on ancient horsetail ferns boggle the imagination, while the slimy banana slug is able to disgust and fascinate all at once. Plants adapt to low light levels on the forest floor, while whole plant and animal communities bustle in the canopy above our heads.
The Muir Woods National Monument is an old-growth coastal redwood forest. Due to its proximity to the Pacific Ocean, the forest is regularly shrouded in a coastal marine layer fog, contributing to a wet environment that encourages vigorous plant growth. The fog is also vital for the growth of the redwoods as they use moisture from the fog during droughty seasons, in particular the dry summer.
The monument is cool and moist year round with average daytime temperatures between 40 and 70 degrees Fahrenheit. Rainfall is heavy during the winter and summers are almost completely dry with the exception of fog drip caused by the fog passing through the trees. Annual precipitation in the park ranges from 39.4 inches in the lower valley to 47.2 inches higher up in the mountain slopes.