Spring tides and weather surge in Cornwall

The tide prediction shows the astronomical tide. The sea you see on the day also includes weather.

What spring tides are

Spring tides are the larger tides in the lunar cycle. They happen around new moon and full moon, when the range between high water and low water is bigger. On the site, spring tides are flagged when a day sits among the larger ranges in the prediction file.

Why weather changes the sea level

Low air pressure lets the sea surface rise. Strong onshore wind can push water toward the coast. Offshore wind can pull it away. These effects sit on top of the astronomical tide, so the true water level can be higher or lower than the curve.

How the live gauge check helps

Each station page compares the latest Environment Agency gauge reading with our prediction for the same minute. The difference is mostly weather surge. When that number grows, treat the timetable with extra caution.

Plan with the bigger picture

For beach walks, look at the next low water and the following high water, not just one time. Check the daily range, read the live gauge difference, and consider wind direction and warnings before committing to a route.