Reading the tide
Cape Cod tide chart: five stations, two tides
Choose a day: the curves of the bay side and the sound side are drawn together, with their times side by side.
| Station | High tides | Low tides | Range |
|---|---|---|---|
| Provincetown | 1:35 AM 9.3 ft · 1:43 PM 10.0 ft | 7:32 AM 0.9 ft · 8:04 PM 0.1 ft | 10.0 ft |
| Plymouth | 1:33 AM 9.7 ft · 1:43 PM 10.6 ft | 7:44 AM 1.0 ft · 8:14 PM 0.2 ft | 10.4 ft |
| Chatham | 2:40 AM 3.9 ft · 2:32 PM 4.6 ft | 7:54 AM 0.9 ft · 8:36 PM 0.3 ft | 4.3 ft |
| Hyannis | 2:45 AM 3.2 ft · 2:39 PM 3.9 ft | 7:52 AM 0.8 ft · 8:40 PM 0.2 ft | 3.7 ft |
| Nantucket | 2:44 AM 3.0 ft · 2:36 PM 3.7 ft | 8:01 AM 0.7 ft · 8:47 PM 0.1 ft | 3.6 ft |
Published by Radif Partners · How the tides are computed · predictions downloaded October 13, 2026
Cape Cod has two tides, and this chart shows them on the same scale. On the Cape Cod Bay side, the tide of the Gulf of Maine averages 9.9 ft at Provincetown and 10.0 ft at Plymouth. On the Nantucket Sound side it shrinks to 3.6 ft at Hyannis and 3.5 ft at Nantucket, because the Atlantic tide wave nearly cancels itself near Nantucket. Chatham's Stage Harbor, at the elbow, averages 4.3 ft. The two sides do not turn at the same time either: compare the curves for any day in the next month. Each station name opens its page, with seven days of times, the year's king tides, the lowest lows and a planner for walks on the flats or a launch at a harbor ramp, so the comparison here leads straight to the details of the place you chose.
Why the sound side barely moves
The tide is a wave that travels around ocean basins. In some places, called amphidromic points, the wave's crests and troughs rotate around a center where the height nearly vanishes. One lies close to Nantucket. The farther a shore is from that point, the bigger its tide: Cape Cod Bay, part of the Gulf of Maine and far from the point, gets the full regional range; Nantucket Sound, near it, gets a fraction. The currents in the sound stay strong even though the water level hardly changes, which surprises boaters used to the bay.
Same town, different water
Several Cape towns touch both sides. Barnstable has its harbor on the bay, predicted by NOAA from Boston with the full height, and Hyannis on the sound with a third of it. In Chatham, Pleasant Bay on the ocean side lags Boston by about two and a half hours. Before a walk on the flats, a clamming trip or a launch, pick the station on the water where you will be, and check its own page for the lag NOAA gives to the harbors and rivers near it.
Using the chart
The chart draws each station's predicted curve for the chosen day on a common vertical scale in feet above MLLW, with a red line at the current time when the day is today. The table gives each station's highs, lows and range. Curves come from NOAA's hourly predictions for these five reference stations. For the islands, Nantucket is on the chart; Martha's Vineyard has a similar small tide.