The Marin Headlands are a hilly peninsula at the southernmost end of Marin County, California, United States, located just north of San Francisco across the Golden Gate Bridge, which connects the two counties and peninsulas. The entire area is part of the Golden Gate National Recreation Area. The Headlands are famous for their views of the Bay Area, especially of the Golden Gate Bridge.

The Headlands sometimes create their own clouds when moist, warm Pacific Ocean breezes are pushed into higher, colder air, causing condensation, fog, fog drip and perhaps rain. The hills also get more precipitation than at sea level, for the same reason. However, despite being relatively wet, strong gusty Pacific winds prevent dense forests from forming. The many gaps, ridges, and valleys in the hills increase the wind speed and periodically, during powerful winter storms, these winds can reach hurricane force.^{[citation needed]} In summer, breezes can still be very gusty, when the oceanic air and fog crosses the hills.

The weather from November through February in the Headlands is dominated by periodic rainstorms that blow in from the Pacific, often originating in the Gulf of Alaska, and give the area the majority of its rainfall for the year. These cloudy, gray, and rainy days often are interspersed with cool but extremely clear ones. As winter turns to spring, the April-to-June weather tends to be dominated by powerful winds, less rain, and clearer skies. Summer days alternate between clear and warm intervals, giving way to foggy and cool periods. September and October bring the highest average temperatures of the year and the longest stretches of clear skies.

The centerpoint of the Marin Headlands skyline is the 920-foot (280 m) Hawk Hill, the lookout point for the largest known flight of diurnal raptors in the Pacific states.

Each autumn, from August into December, tens of thousands of hawks, kites, falcons, eagles, vultures, osprey, and harriers are funneled by the peninsular shape of Marin County into the headlands. Hawks avoid flight over water since warm thermals that provide lift are rare. Abundant populations of small mammals protected by the park are one resource that helps maintain the large number of visiting raptors in the Headlands during the fall, but the strong onshore winds hitting the hills of the Headlands provide cold updrafts and hot late-summer days provide warm thermals that allow these birds to fly more efficiently.

Volunteers with the Golden Gate Raptor Observatory count and track this fall migration using bird-banding and radio-tracking techniques, all in cooperation with the National Park Service.

The Marin Headlands are also home to black tail deer, mountain lions, bobcats, two types of foxes, coyotes, wild turkeys, hares, rabbits, raccoons, and skunks. In 2003, there was a reported sighting of a black bear in the Headlands; the report was lent credence by a 2012 finding of bear scat on a hiking trail in the Kent Lake watershed, and another sighting on the Point Reyes National Seashore in 2011. River otters inhabit the freshwater lagoons and streams. Large numbers of water birds also migrate through the Headlands, including brown pelicans from May through October; and grebes, egrets, and great blue herons in the spring, summer, and fall. The Headlands' status as a park protects the habitat and populations of these animals within just a few miles of San Francisco and its suburbs.

In the waters surrounding the Headlands, harbor seals can be found year-round, gray whales can be seen in the spring and fall, and seabirds such as common murres and surf scoters swim within sight of shore.