Half Moon Bay tides today

Pillar Point and the open coast

Half Moon Bay is the crescent of beach that curves south from Pillar Point, the headland that shields the harbor at Princeton from the northwest swell. Outside that headland the reef runs out toward deep water, and the big-wave break of Mavericks lies offshore. Inside the breakwater the gauge records a tide of 5.6 ft on an average day, 7.4 ft at spring tides. That is the tide of the open Pacific, a little smaller than the 5.8 ft measured at the Golden Gate, and it holds with little change along the coast from Pacifica to the beaches south of town.

Over the hill, a different bay

The NOAA stations closest to this one on a map are not on this coast at all. They lie on the San Francisco Bay shore of the peninsula, ten to twelve miles away over the ridge, and their water reaches them the long way, through the Golden Gate. NOAA predicts Coyote Point Marina from the Golden Gate gauge with high water 42 minutes later, low water 68 minutes later and highs at 129 percent; Point San Bruno is 38 minutes later at high water. Someone who launches on the bay in the morning and walks the Half Moon Bay beach in the afternoon is dealing with two separate schedules, and the bay side can be close to an hour behind.

The reef flats north of the harbor

Just north of Pillar Point, at Moss Beach, the Fitzgerald Marine Reserve protects a broad, flat reef that comes out of the water on the lower tides. On 232 days of the prediction period at least one low falls below the chart zero. The list of negative low tides sorts them by depth and by daylight.