Rockland Tide Chart

Each day lists the times the water reaches its highest and lowest points at NOAA station 8415490 (Rockland), in station local time, with the predicted height in feet next to each. Heights are measured above mean lower low water (MLLW), the zero on NOAA charts, so a minus tide is water lower than an average day's lower low. The curve shows how the water moves between those points: roughly two thirds of the change happens in the middle two hours between a high and a low.

Zero is not the sea floor and not the beach: it is MLLW, the long-term average of the lower of each day's low waters at this station. A prediction of 0.0 ft means the water will stand at that average lowest level. Negative predictions (minus tides) fall below it and expose ground that most days never uncover, which is why tidepoolers and clam diggers hunt for them.

They are astronomical predictions from harmonic analysis of water level records at Rockland, and for timing the rhythm of high and low they are excellent. What they cannot include is weather: sustained wind, pressure changes and river flow routinely push the observed water level above or below the prediction. NOAA's own disclaimer says the data are based on the latest information available as of the date of your request and may differ from the published tide tables.

The useful window is roughly the hour either side of a good daytime low, and the best days are minus tides, when the predicted low falls below the MLLW datum. This page derives both from NOAA's predictions for the next 7 days and flags them in the windows section. Harvesting rules, licenses and closures are set by Maine authorities, so check the state's shellfish and beach regulations before collecting anything.

Yes, it is the main driver. Around new and full moon, Rockland gets spring tides: the month's biggest highs and lowest lows. Around the quarter moons the range shrinks (neap tides). NOAA's mean range for this station is 9.78 feet, and the actual swing breathes around that number with the lunar cycle, which is why this page shows the moon phase beside every day.

For boating and navigation, use NOAA's official charts, tide tables and current predictions at tidesandcurrents.noaa.gov. The predictions here are for planning beach visits, fishing sessions and tidepooling. And no tide table can say whether a specific sandbar, flat or crossing is safe to walk; that depends on local conditions and is a question for whoever manages that shoreline.

From NOAA station 8415490, Rockland, a harmonic tide prediction station at 44.105, -69.102. Your browser requests the predictions directly from NOAA CO-OPS (api.tidesandcurrents.noaa.gov) when the page loads, so the numbers are NOAA's own, not a copy we maintain. NOAA updates its prediction stations quarterly; this page follows those updates automatically because it reads the live service.