The Moon and Sun drive the astronomical tide, but the water level observed at the coast also responds to local geography and weather. Continental shelves and the shape of the shoreline can magnify or reduce a tidal wave. Funnel-shaped bays and estuaries may amplify the range, while shallow water, narrow inlets, and friction can delay or weaken it. Strong river flow can also alter or temporarily mask a tide in an estuary.
Wind and air pressure can move the observed water away from the predicted curve. Persistent onshore wind can pile water against the coast, while offshore wind can push it away. Low atmospheric pressure generally allows water levels to rise; high pressure can depress them. Storm surge, waves, rainfall, and river discharge can add further short-term effects.
A tide prediction describes the expected astronomical cycle. It is not the same as an observed water level or a complete coastal weather forecast. Tide Guide places available weather and marine conditions beside the tide to provide more context, but conditions vary by station and provider. For navigation or hazardous coastal conditions, check current local observations, forecasts, and official warnings.
Source: NOAA Tides and Water Levels